Machine Coolant Waste Reduction By Optimizing Coolant Life

1 a

June 1988

MACHINE COOLANT WASTE REDUCTION BY OPTIMIZING COOLANT LIFE

Joseph Pallansch Washington Scientific Industries, Inc.

2605 Wayzata Boulevard Long Lake, M N 55356

Project Officer

James S. Bridges Office of Environmental Engineering and Technology Demonstration

Hazardous Waste Engineering Research Laboratory Cincinnati, OH 45268

This study was conducted through

Minnesota Waste Management Board S t . Paul, MN 55108

and the

Minnesota Technical Assistance Program University of Minnesota Minneapolis, MN 55455

HAZARDOUS WASTE ENGINEERING RESEARCH LABORATORY OFFICE OF RESEARCH AND DEVELOPMENT

U.S. ENVIRONMENTAL PROTECTION AGENCY CINCINNATI, OH 45268

This project was partially supported with a United States Environmental Protection Agency cooperative agreement through the Minnesota Waste Management Board and the Minnesota Technical Assistance Program.

Although the research described in this report has been funded in part by the United States Environmental Protection Agency through a cooperative agreement, it has not been subjected to Agency review, and therefore does not necessarily reflect the views of the Agency and no official endorsement should be inferred.

Table of Contents !?age

Abstract .................................................... ii

Figures ..................................................... iii

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

Project Description ......................................... 2

Methods and Materials Coolant ................................................ 2 Machine Tools . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 Skimmers ............................................... 3 Centrifuge . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 Waste Management Building .............................. 4

Procedures Baseline Sampling and Analysis ......................... 4 Time-and-Motion Studies ................................ 5 Ongoing Sampling and Analysis .......................... 6

Results and Discussion Change Practice ........................................ 6 Coolant Maintenance .................................... 6 Centrifuge ............................................. 8 Blasocut 2000 Coolant .................................. 8 Chip Handling .......................................... 8

Summary and Conclusions ..................................... 9

Recommendations ............................................. 9

References .................................................. 10

Appendices Appendix A . Characterization ......................... 1-8 Appendix B . Monitoring & Analysis . I . . . . . . . . . . . . . . . . . 8-16 Appendix C - Monitoring & Analysis - I1 ................ 16-25 Appendix D - Conclusions & Recommendations . . . . . . . . . . . . . 26-29 Appendix E - Treatability .............................. 30-35

ABSTRACT

Machine shops use coolants to improve the life and function of machine tools. These coolants become contaminated with oils with use, and this contamination can lead to growth of anaerobic bacteria and shortened coolant life. This project investigated methods to extend coolant life through improved coolant maintenance, with the goal of reduced volumes of coolant waste.

Skimmers to remove oil from the surface of coolants were found to be cost-effective. Use of a centrifuge was a l s o tested. Coolant change practices were documented, and modified for improved coolant life. A specific coolant with wide applicability and tolerance was tested and found to have a life of at least seven months using the documented procedures.

ii

. Figures

Numllsr Page

1 Machine Tools in Project Study Group .............. 3

2 Results of Recycled Coolant Sampling.. ............ 7

iii

I NTROD UCT ION

The function of a machine shop is to remove metal from stock, which may be in t h e form of castings;bars, extrusions, or forgings. The object of this metal removal is to create a part, which may be used as is or which may become part of an assembly, A machine is used to hold the stock (the "work") and the device doing the metal removal (the "tool"). This removal may be performed by cutting (drilling, grinding, sawing) or shearing. In the process, heat is generated by the friction between the tool and the work. A coolant, applied directly to the tool and work, is used to transfer this heat, which results in:

o Longer tool life o Increased cutting performance o Maintenance of dimensional stability of the work

The coolant is collected in and recirculated from a sump. After a period of time, contaminants which mix with the coolant contribute to its breakdown, at which point the coolant is replaced and disposed as waste.

The two major contaminants of coolant are chips of metal removed from the work and lubricant ("way oil"). The chips fall continuously from the work as it is processed. Most are collected using screens, conveyors, and sweeps, but some fall into the sump, from which they must be periodically removed by filtering the coolant and cleaning the sump. Way oil enters the coolant by dripping from the flat surfaces called ways which slide against each other in three axes of motion to position the work against the tool. This oil contamination ("tramp" oil) must be removed continuously or periodically using skimmers, filters, centrifuges or disposal. If chips and way oil are not removed, conditions become increasingly favorable for the growth of anaerobic bacteria. This leads to formation of objectionable sulfide- containing compounds, e.g., hydrogen sulfide, and can shorten the life of the coolant by altering its chemical balance.

Coolant sumps contain from 20 to 100 gallons each and, depending on maintenance practices, the coolant may require monthly replacement. Even a small shop will have several machines, and some shops have up to 100 and more. Combine this with the use of several kinds of coolant and the disposal requirements and expense can become very burdensome. Standard waste management practice for this wastestream involves one or more of the following steps: o Pump waste coolant into holding tanks or drums o Skim tramp oil and segregate for energy recovery o Treat coolant to break oil/water emulsion o Separate oil and segregate for treatment/disposal o Treat and/or sewer remaining water

The exact management scheme is determined by the type of coolant, level of contamination, presence of regulated materials (metals, organic solvents), and availability of treatment. Disposal costs vary from $20 to $200 per 55-gallon drum depending on management required.

1

Project Description

Washington Scientific Industries (WSI) is a machine shop which uses a wide variety of tools to make parts from materials such as steel, aluminum, copper, and stainless steel. The machines used are medium-sized and are similar to those used in many machine shops. Waste coolant generated by WSI is contaminated with way oil and chips. Previous management of waste coolant involved the following steps:

o Monitor coolant (several types) for function and odor o Remove coolant and clean sump (frequency variable by machine) o Replace with new coolant o Segregate chips for recovery as scrap o Coolant/oil mixture collected by hauler for treatment and

disposal

The volume of waste coolant generation is affected by business activity, but averages 120 55-gallon drums per year, with a management cost, including machine maintenance, handling, disposal, and replacement of $150 per drum. An extension of coolant life would result in a reduction of coolant waste generation and direct cost savings.

The project conducted under the auspices of this research grant was designed to study the following:

o A specific water-soluble coolant (Blasocut 2000 Universal) in

o Coolant maintenance practices associated with three types of

o Health effects on workers of coolant through use and handling o Chip/coolant separation o Oil/water separation

use with a variety of machines, tools, and materials

machines

The aim is to identify factors and techniques which contribute to coolant life extension, and to document procedures and effects of the entire coolant life cycle. This information is seen to be useful for decision-making by other machine shops.

Machines chosen for the project are one to four years old, used for jobs with long (2-4 week) production runs. Operators, material and process were held constant as much as possible. Standard industrial engineering practices were used to determine direct and indirect labor required for coolant change practices, coolant maintenance, waste handling, and waste containment. Sampling was done to establish a baseline for new coolant, way oil, coolant dilution water, air quality, and health effects.

Methods and Materials

Blasocut 2000 Universal is a mineral oil based, water-soluble metal-working fluid. It is a cooling lubricant intended for use with all chip-forming operations except grinding and all materials except magnesium. The concentrate is made up of 60% refined mineral oils, to which emulsifiers are added in the form of non- ionogenic components. This reduces the interfacial tension of

2

oil/water phases to such a low level that a mixture yielding a fine dispersion of oil in the water is possible. Corrosion inhibitors are also added to protect the work from the effects of the water carrier fluid. No biocides are present in the concentrate, nor are any required for the maintenance of the solution. The cost of the concentrate (1985) is $9-12 per gallon, depending on packaging.

Machine No.

1723

1 7 1 4

3806

*

1720

4719

This coolant was chosen because of its applicability to a wide variety of operations and materials. It tolerates (and in fact requires) hard water as a component, and it does not contain nitrites or other materials which can adversely affect worker health. It was thought that using only one coolant in as many machines as possible would simplify the entire waste management scheme and allow for efficient coolant maintenance. The literature indicates that this coolant can be recycled extensively, thus cutting waste volumes. One of the objectives of this project was to determine the exact steps needed to accomplish this waste reduction via recycling.

Machine Type Material Processed

Lathe M tool steel Mori-Seiki

Lathe H copper Hitachi-Seiki

Broach aluminum castings Ohio Broadh and Tool

Lathe 0 stainless steel Okuma

MMC aluminum castings Niigata

L

Two disc skimmers were used, differing only in the method used to remove oil from the disc after the oil lifted from the coolant. Both cost approximately $100, and are representative of several models widely available. It is important to have proper access in order to monitor skimming activity and provide space for a receptacle to collect skimmed tramp oil. In order to use these skimmers, because of their configuration, i.t was necessary t o modify several coolant sumps to provide the required access and mounting space. This is a very common problem with machine tools, many of which are built with totally or nearly enclosed sumps, or sumps only accessible through a secured cover.

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A belt skimmer was also used in order to test a claim of a higher rate of removal of tramp oil than that possible using a disc skimmer, Because of its configuration, this skimmer was mounted as a mobile unit and tested on several machine tools. Also because of its configuration, it was possible to mount this skimmer in such a way that skimmed tramp oil drained into a 5 5 - gallon drum, unlike the disc skimmer, which must drain into low containers that require frequent emptying. A timer was added so that the belt skimmer would run intermittently, allowing time for sufficient tramp oil to collect for efficient removal.

For all skimmers tested, it was sometimes found necessary to operate a small paddle pump in the coolant sump to create a circular surface flow and move tramp oil closer to the skimmer. This was important to minimize the amount of coolant collected with the tramp oil. This contamination of tramp oil by coolant can lead to later disposal problems.

A small centrifuge was modified to function as a mobile unit. It was thought that this approach to coolant maintenance, while more costly, could sufficiently clean the coolant occasionally by removing all tramp oil, rather than relying on a continuous, partial removal. An operator was assigned to use the centrifuge to clean the coolant in 25 machine tools, a time-and-motion study was performed to track labor costs. Chips were not removed from the sump being cleaned.

Shortly before this project began, WSI completed construction of a building expressly for the collection and storage of chips from machine tools and for storage of solvents. In the past, many machine shops had several watertight hoppers outside their building holding chips awaiting transport to scrap dealers. More recently, these hoppers have been perforated with drain holes in order to improve the handling of scrap. However, these drainholes allow the escape of not only rainwater, but also draining coolant and oils. This could lead to groundwater contamination.

WSI addressed this problem by placing sloped floors in an enclosed building, on which rest 20 cubic yard roll-off Containers. Coolant and oils drain from the chips in these containers to a trench, and from there are collected in barrels for proper disposal. Chips from the machine tools are collected in modified 55-gallon drums which can be emptied by an operator with a forklift into large carts. These carts are then also emptied by forklift into the containers in the waste management building.

Procedures

In order to more accurately track any changes during the project, the first phase of the project consisted of gathering baseline data on several parameters. All sampling and analysis was performed by an independent consulting laboratory.

Continuous operation of the disc skimmers tended to yield considerable contamination of the skimmed tramp oil b y intermixed coolant. Collection of the skimmed oil from small containers proved inefficient and losses from full containers was common. The belt skimmer, operated with a timer on a schedule of 5-10 minutes/half hour, yielded tramp oil with very little coolant contamination. In addition, the option of using a 55-gallon drum for collection of tramp oil proved superior for efficiency as well as spill control.

Machine No.

The following table summarizes changes in the key parameters over the life of the project.

Date

1723 7/87 9/87 10/87 12/87 1/88

1714 7/87 9/87 10/87 12/87 1/88

3806 7/87 9/87 10/87 12/87 1/88

% Coolant

4719

Figure 2.

Oil and Grease mg/ 1

7/87 9/87 10/87 12/87 1/88

-

2.5 4.5 4.5 4.5 6.0

2.5 4.5 7.0 11.0 10.0

2.0 10.0 4.5 16.0 13.0

3,600 20,000 25,000 31,000 14,200

1,300 25,000 32,000 47,000 20,500

2,000 37,000 18,000 72,000 39,000

2.5 1.5 2.0 2.0 2.0

~

1720

4,400 2,900 6,200 27 , 000 8,400

7/87 9/87 10/87 12/87 1/88

1.0 2.0 5.0 4.5 4.5

6,600 43,000 49,000 36,000 12,000

Total Bacteria Plate Count, Colonies/ml

Total Suspended Solids, mg/l

100,000,000 71,000,000 115,000,000 160,000,000 130,000,000

720 800 2100 1500 690

3 , 500,000 23,900,000 14,400,000 45,000,000 69,000,000

720 160

1700 5400 8400

140,000,000 93,000,000 107,000,000 64,000,000 167,000,000

1400 880

4000 750 800

100,000,000 78,800,000

246,000,000 252,000,000 310,000,000

130,000,000 74,800,000 57,000,000 150,000,000 167,000,000

84 400 620 3100 1400

41 470 360 1400 1100

The percent coolant remained in the stable range, and while fluctuations are seen they are not significant. In general, the oil and grease concentrations increased for most of the machines evaluated until January 1988, when oil and grease concentrations dropped dramatically. This is the point at which skimmers were in use consistently to remove tramp oil. Other concentration drops are traceable to other, more intermittent use of skimmers.

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Total bacteria plate count appears to increase throughout the project, finally stabilizing roughly in the range of 150,000,000 colonies per milliliter of coolant. This is not extremely high, and, in fact, populations of 250,000,000 and more are common. Where reductions in oil and grease concentrations were observed, increases in total bacteria plate count were often observed. This is explained by noting that a reduction in oil and grease concentrations favors aerobic conditions, thus reducing the possiblity that fungal agents or anaerobic microorganisms may be present. This is extremely favorable for extended coolant life.

A mobile centrifuge was tested on a group of 25 machine tools not in the study group. The size of this group was determined by the length of time required to set up and operate the centrifuge: when cleaning of the 25th machine tool was completed, the first needed cleaning again. The determining factor seemed to be setting and adjusting a float in each sump which could account for fluctuating coolant levels. The entire procedure of hooking up, adjusting, and coolant cleaning required approximately one day per sump. Once running, the centrifuge performed well cleaning the coolant. Other, lingering, problems included chips plugging the intake and oil fouling the float. Overall, it seemed that use of the centrifuge to clean coolant, at least in the mobile configuration, is not efficient. The test was repeated twice, but results indicated that the capital investment could not be justified over continuous cleaning by skimming.

The coolant, even after being recycled for seven months, meets or exceeds metal removal rates for aluminum, steel, copper, and stainless steel. It has shown the ability to tolerate increased concentrations of oil and grease while not yielding to increased activity of anaerobic bacteria. The use of recycled Blasocut 2000 also does not appear to be associated with any increase in adverse skin conditions or dermatitis, as supported by interviews and photographs of operators’ hands.

Lab research also indicates that when the coolant must be disposed, an oil/water separation can be accomplished by lowering the pH to between 3 and 4 and allowing approximately two hours for the oil fraction to separate. The oil can then be skimmed and accumulated for disposal. Analysis indicated elevated levels of copper and zinc ( 2 . 5 - 3 . 5 mg.1 copper; 8-10 mg/l zinc) in the remaining water fraction. Disposal of this solution by sewering would require further evaluation.

The system for collecting and storing chips before salvage proceeds as follows:

1) Operator collects chips in 55-gallon drum mounted on dolly 2) When drum is full, it is wheeled to an aisle

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3 ) Forklift operator empties drum into cart, segregating metals

4 ) Forklift operator empties carts into appropriate containers and discarding trash

in waste management building

This procedure saves operator time, improves salvage quality of the chips, and collects approximately one 55-gal lo^ drum per month of coolant and oil which drain from the collected chips. Air sampling in the waste management building indicates no misting of oil, and the highest concentrations for any of the compounds documented represent approximately 0 . 2 % of the OSHA Permissible Exposure Limits.

Summary and Conclusions

The results of tests conducted during this project indicate that i t is possible to extend the life of machine tool coolant significantly and thereby reduce the volume of waste coolant generated.

It seems important to use a coolant and way oil with wide applicability and suitability for recycling. Key factors seem to be tolerance of hard water, resistance to anaerobic bacteria growth, and stability over a range of concentrations.

The project found that simple skimming of tramp oil using any of several different methods was cost-effective and reduced oil and grease concentration significantly. This proved sufficient to extend coolant life to at least seven months, where previously used coolant may have been changed as often as weekly.

Recommendations

While use of a single coolant is proving possible for 90% of the requirements of WSI, many machine shops may balk at changing their coolants. Further research is needed on the coolant maintenance and change practices documented in this project and their effect on the life of a variety of coolants. Research is also needed on alternate tool and work cooling methods and schemes for preventing contamination of coolant by way and hydraulic oil.

9

References

Blaser - Research of existence of micro-organisms Coolants Problematic of Micro-organisms in Metalworking Fluids; Sodium Nitrite in Water-Soluble Cutting Fluids; Questions and Answers on Dermatitus: Facts for Metal Workers; Skin Tests with BC at the Klinikum Johann Wolfgang Goeth

Mutagenic Potential Study of Blasocut; Health & Safety Tests and Studies with Blasocut products; List of chemicals NOT CONTAINED in Blasocut products; Summary of Toxicological Characteristics of Blasocut products; Information and Procedure of Coolant Disposals.

University;

Connelly - "Machine Tool Reconditioning," Ma~hin_e l'Cgll 1_9$3Q.

Dull - "Modern Chemistry," Holt, 1982.

Kerzner - "Project Management, '' Van Nostrand, 1984.

Klaus - "Finite Element Procedures in Engineering Analysis," Prentice Hall, 1982.

Lindberg - "Processes and Materials of Manufacturing," Allynd Bacon, 1968.

Moore - "Foundations of Mechanical Accuracy," Moore, 1970.

Niebel - "Motion and Time Study," Irwin, 1982.

Oberg - Machinery's Handbook, Industrial Press, 1980.

Peckner - Handbook of Stainless Steels, McGraw Hill, 1977.

Stoughton - Engineering Metallurgy, McGraw Hill, 1953.

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Appendix A

Characterization

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COOLANT WASTE REDUCTION PROJECT PACE PROJECT NUMBER 870611.361

MS H I N G T O N SCIENTIFIC INDUSTRIES, INC. LONG LAKE, MINNESOTA

I. INTRODUCTION

Washington Scientific Industries, Inc. i s currently evaluating methods of minimizing oil/water waste generated by machine tooling operations. This investigation is being conducted under a grant from the Minnesota Technical Assistance Program (MnTAP) through the University of Minnesota. As part of this project, PACE Laboratories, Inc. (PACE) has provided sampling and analytical services to evaluate the quality of water-soluble coolants and the air quality in the waste management building at the Washington Scientific Industries ( W S I ) facility in Long Lake, Minnesota. In addition, a PACE industrial hygienist has conducted informal interviews with machine operators in conjunction with each sampl i ng event.

In order t o track the quality of the water-soluble metalworking coolant, analyses were performed to determine the approximate percent of coolant concentrate, the concentrations of o i l and grease, total suspended solids, total bacteria (standard plate count), and concentrations of various organic compounds. The coolant chosen for this study was Blasocut 2000, produced by Blaser Swisslube, Inc.

Prior t o implementation of the coolant recycling program, baseline samples of the coolant dilution water, the unused Blasocut 2000 coolant and the Mobil Vactra 2 Way Oil were collected o n June 29, 1987. Since no organic compounds were found in the coolant sample, the dilution water sample was not analyzed. Air sampling in the waste management building had been performed by WSI prior t o the coolant waste reduction project, therefore additional baseline air samples were not believed t o be necessary.

Specific analyses performed both on the base1 ine samples and subsequent coolant samples were chosen for specific reasons. The approximate percent Blasocut ZOO0 was evaluated by refractometric methods to verify that the coolants remained in the stable range for oillwater emulsions. Please refer to Figure I, attached.

Oil and grease concentrations were determined since way oil used during the machining process becomes mixed with the water soluble coolant in the machine sump. Excessfve oil concentrations can lead t o pooling of oil on the surface of the coolant. Such a condition favors anaerobic bacteria formation. Anaerobic bacteria are associated with the production of hydrogen sulfide (H2S>, and other objectionable sulfur-containing compounds. Oil and grease analysis is also important t o verify that the proper oil to water ratio i s present in the coolant emulsion. Specific efforts have been focused o n removing oil from the coolant sump directly. Thus, oil and grease values may vary from machine to machine.

Through the machining process, metal chips enter into the coolant reservoir. Most of these cuttings readily settle out and are transported t o the waste management building for recovery of oil and coolant which have settled on the surface o f the metal chips. Finer metal particles and debris may also enter into the coolant. The total suspended soilds analysis determines the extent to which these finer particles may affect coolant quality.

Bacteria are present in all water-soluble metalworking coolants. It is not unusual to see a quarter of a billion bacteria colonies per mi 1 1 1 1 i ter (ml) of coolant. Simi lar quanti ties of bacteria are present in pasteurized milk. Specific identification o f the bacteria present was not deemed necessary, since the avai lable 1 1 terature indicates that 99.9 percent of the micro-oganisms present i n adequately aerated coolant are non-pathogenic.

An organic compound scan was performed o n both the way oil and the coolant, t o determine if any organic contaminants may have entered into the coolant.

In addition to the organic compound scan, the way oil was evaluated for various metals which may be present as additives In some petroleum oils. These compounds included arsenic, cadmium, chromium and lead.

Baseline sampling results are included in the following tables:

I -A Coolant water analysis

I-B Unused coolant sampling results

I-c Organic compound scan results

1-0 Metals analysis results

I-€ Organtc vapor sampling results

As shown in Table I-A, the coolant dilution water has a relatively high total hardness measurement. All of the parameters shown in Table I-A are within the desirable range. The specific water soluble coolant chosen reportedly works well with hard water.

The unused coolant, as shown In Table I-B, contained approximately three percent of the coolant concentrate. The remaining parameters are shown for future reference.

A s shown in Tables I-C and I-D, no metals o r organic compound contaminants were found in either the 6lasocut'2000 coolant or the Mobil Vactra Number 2 Way Oil.

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The air quality in the waste managment building was monitored by WSI on January 9, 1987. The results were below the respective analytical detection limits for l,l,l-trichloroethane and stoddard solvent, as measured on January 9, 1987. The only compound detected was Freon 113. The results shown on Table I-E represents less than 0.2 percent o f the OSHA Permissible Exposure Limit (PEL). Please note that, based o n observations made subsequent t o the baseline air sampling, the parameters were changed to l,l,l-trichloroethane and methylene chloride to reflect the materials observed in the building with the lowest PEL’S.

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TABLE I-A

COOLANT WATER ANALYSIS PACE PROJECT NO. 870611.361

WASHINGTON SCIENTIFIC INDUSTRIES, INC. LONG LAKE, MN

Sample Col 1 ected September 3 , 1985

B1 aser Specifications

For Water Parameter Ouali tv

PH 6-7.5

Total hardness 178-356

Chl or i de <20

Sulfate < 20

Nitrate <lo Chemical 02 demand < 20

WSI We1 1 Water

Qualitv w 7 . 4

31 3 mg/L CaC03

2 mg/L

10 mg/L

<O. 5 mg/L

0.5 mg KMn04/L

NOTES :

1 ) Analysis was performed by Culltgan U.S.A.

2 ) I t<' ' means less than stated value.

3) Blaser speclflcations are as described i n papers by W. Lehmann f n Technfsche Rundschau. 23 & 26 (1 9 7 6 ) .

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TABLE 1-6

UNUSED COOLANT SAMPLING RESULTS PACE PROJECT NO. 870611.361


Total Total Refractometer O i 1 and Bacteria Suspended

Sampl i ng Reading, Grease, Plate Count, Sol ids, Date Descrlotlon X Coolant ma/L Q l o n l e s / m l ma/L

t i m / a 7 Unused Coolant 3.0 7 9 600 1 1

NOTES :

1 ) The refractometer reading was made using an America1 Optical hand-held refractometer Model No. 10440. Readings were corrected accordlng t o the calibration curve shown in Figure I.

2) %g/L" means millfgrams per liter o f coolant.

3 ) " m l " means milliliters o f coolant.

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TABLE I-C

ORGANIC COMPOUND SCAN RESULTS PACE PROJECT NO. 87061 1.361

WASHINGTON S C I E N T I F I C INDUSTRIES, INC. LONG LAKE, MN

Samples Collected on June 29, 1987

Concentrat 1 on B1 asocut Mob1 1

Paramete r Unlts

M e t hano 1 Ethanol Methyl ene chl o r i de Ace tone Isopropyl alcohol n-Propanol t-Butanol Tetrahydrofuran Chloroform 1,1,2-Trichloro-l,2,2,-

t r i f luoroe thane Methyl e thy l ketone 2-Butanol 1 , l ,1-Trichloroethane Ethyl acetate 1,1,2-Trichloroethane n-Butanol Benzene Hexane Cyclohexanone Methyl isobuty l ketone 1,1,2,2-tetrachloro-

e thy1 ene Butyl acetate Heptane To1 uene Ethyl benzene Xylenes Total unknown peaks High b o i l i n g compounds

x x x x x x x x x x x x x x x x x x x x x x x x x x x x

MDL

0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1

0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1

0.1 0.1 0.1 0.1 0.1 0.1 0.1

2000 GQQl-uL

ND ND ND ND ND ND ND ND ND ND

ND ND ND ND ND ND ND ND ND ND ND

ND ND ND ND ND ND ND

V a c t r a 2 Wav 011


ND ND ND ND ND ND ND ND ND ND ND


NOTES: 'IMDL" means ana ly t i ca l method detection 1 i m i t IIND" means not detected a t o r above MDL

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TABLE I -D

Par ame k r

A r s e n i c

Cadmi um

Chromium

Lead

NOTES :

METALS ANALYSIS RESULTS PACE PROJECT NO. 870611.361


Samples C o l l e c t e d on June 2 9 , 1987

Mobi 1 V a c t r a 2

Units w Way 01 1

1 . 2 NO

1 ) IIMDL" means a n a l y t i c a l method d e t e c t i o n 1 i m i t 2) "ND" means n o t d e t e c t e d a t or above MDL

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TABLE I-E

ORGANIC VAPOR SAMPLING RESULTS HASTE MANAGEMENT BUILDING

PACE PROJECT NO. 870611.361


Samples Collected on January 9, 1987

Concentration. pom Sampl i ng

Samp 1 e T i me Stoddard De scr i D t i on Loca t ion M f n . Freon 113 22 Sol vent

Area Sample ' Floor level 60 ~0.7 < 1 < 1

Area Sample 5 ft. height 60 1.6 < 1 < 1

OSHA Permissible Exposure Limits (PEL'S): 1000 350 500 ACGIH Threshold Limit Values (TLV's): 1000 350 100

NOTES: 1 ) Samples were collected by Washington Scientific Industries, Inc. using 3M Diffusion Monitors (No. 3510) and analyzed by 3M

2) "ppmll means parts per million

3) Chemical abbrevlatlons: 1,1,2-trichloro-1,2,2-trifluoroethane (Freon 113) 1,l.l-trichloroethane (TCA)

4 ) VIt means below stated value (airborne detection limit)

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11. ANALYTICAL RESULTS AND OBSERVATIONS:

July through October, 1987

The following discusses results o f coolant evaluations, air sampling, and employee interviews performed on July 23, September 22 and October 15, 1987. Ongoing coolant recyling was performed from late June, 1987 through October, 1987. Subsequent sampling in December, 1987 and January, 1988 will be the subject of a subsequent report.

Samples of Blasocut 2000 coolant from five machine tools was evaluated for percent coolant, oil and grease, total bateria plate count, and total suspended solids. The unit of measurement for the coolant concentration i s percent (%), the unit for oil and grease and total suspended solids concentrations i s milligrams per liter of coolant liquid. Total bacteria plate count i s measured in bacterial colonies per milliliter o f coolant.

The results for each of these parameters i s shown for three different sampling events. A separate table presents data for each of the five machine tools evaluated.

As shown in Tables 11-A through 11-E, the o i l and grease concentration appears t o have increased over time for most of the machine tools evaluated. The total bacteria plate count does not appear to be directly associated with the o i l and grease concentration. The total suspended solids appears to have increased for most of the machines evaluated.

The results shown in Tables 11-A through 11-E appear t o be normal. It should be noted that the manufacturer of the water-soluble coolant (Blaser Swisslube, Inc.) has not published criteria concentrations for oil and grease and total suspended solids, since appropriate amounts may vary with the specific application. The total bacteria plate count for all of the samples appears t o be within the expected range.

The results of air sampling in the waste management building were well below the respective OSHA Permissible Exposure Limits for l,l,l-trichloroethane and methylene chloride.

Interviews with machine operators indicated that none of the operators had experienced dermatitis since using the recycled Blasocut 2000. One employee, however, indicated that he had a history of boils on his left arm which dated back t o May o r June o f 1987. The causative agent for this problem has not been determined.

Photographs were taken to document the baseline condition of the machine operators' hands. Subsequent photographs will be taken for the same employees in January of 1988 for comparison to determine whether any significant changes have occured.

-9-

Appendix B

Monitoring and Analysis - I

TABLE 11-A

MACHINE NO. 1723 COOLANT SAMPLING RESULTS



Total Total Refractometer Oi 1 and Bacteria Suspended

Sampl i ng Reading, Grease, Plate Count Sol ids, Date Descr i Dt 1 on 7. Coolant ma/L Colonies/ml mq/L

7/23/87 Recycled coolant 2.5 3,600 100,000,000 720

9/22/87 Recycled coolant 4.5 20,000 71,000,000 800

10/15/87 Recycled coolant 4.5 25,000 115,000,000 2,100

NOTES :

1 ) Machine No. 1723 i s a Mori-Seiki unit and runs ferrous metal parts using Blasocut 2000.

2 ) Refractometer readings were made using an American Optical hand-held refractometer Model No. 10440. Readings corrected accordlng to the calibration curve shown in Figure I.

3) %g/L" means milligrams per liter of coolant.

4) "ml" means mi 1 1 1 1 i ters of coolant.

-1 0-

TABLE 11-B




Tota 1 Total Refractometer O i 1 and Bacteria Suspended

Sampl i ng Reading, Grease, Plate Count, Sol ids, Date Des cr i D t 1 on % Coolant ma/L Colonies/ml mq/L

7/23/87 Recycled Coolant 2.5 4,400 3,500,000 720


10/15/87 Recycled Coolant 2.0 6,200 14,400,000 1,700

NOTES: 1 ) Machine No. 1714 Is a Hitachi-Seiki unit and runs low-carbon steel and copper parts using Blasocut 2000.

2) Refractometer Readings were made using an American Optical hand-held refractometer, Model No. 10440. Readings were corrected according to the calibration curve shown in Figure I.

3) "mg/L" means milligrams per liter of coolant.

4) The coolant in Machine 1714 was last changed in June, 1987.

5 ) "ml" means milliliters of coolant.

-1 1 -

TABLE 11-C



WASHINGTON S C I E N T I F I C INDUSTRIES, I N C . LONG LAKE, MN

Refractometer Oil and Total Bacteria Total Sampl i ng Reading, Grease, P1 ate Count, Suspended Date ks c r i p t i on "/,Coolant ma/L Colon ies/ml Solids. ma/L

7/23/87 Recycled Coolant 1 .o 6,600 140,000,000 1,400

9/22/87 See Note (4) 2.0 43 * 000 93,000,000 880


NOTES: 1 ) Machine No. 3806 is an Ohio Broach and Tool unit and runs aluminum parts using Blasocut 2000.

2) Refractometer readings were made using an American Optical hand-held refractometer, Model No. 10440. Readings were corrected according to the calibration curve shown in Figure I.

3) 9ng/Ltt means mi 1 1 igrams per 1 1 ter of coolant.

4) Fresh coolant was added to reservoir on September 21, 1987 but none was removed.

5 ) means mi 1 1 i 1 1 ters of coolant

-1 2-

TABLE 11-D




Refractometer 011 and Total Bacteria Total Sampl 1 ng Readi ng, Grease Plate Count, Suspended Oa te Desc r i pt ion % coo lant ma/L Colonieslml Sollds. m a l l



10/15/87 Recycled Coolant 7 32,000 246,000,000 620

NOTES: 1 ) Machine No. 4719 is a Niigata unit and runs aluminum parts using Blasocut 2000.

2) Refractometer Readings were made using an American Optical hand-held refractometer, Model No. 10440. Readings were corrected according to the calibration curve shown in Figure I.

3) '@mg/L" means milligrams per liter of coolant.

4) @@ml" means mi 1 1 i 1 i ters of coolant.

-1 3-

TABLE 11-E



WSHINGTON SCIENTIFIC INDUSTRIES, INC. LONG LAKE, MN

~

Refractometer Oil and Total Bacteria Total Sampl 1 ng Read 1 ng , Grease Plate Count, Suspended Date Des cr i D t i on X Coolant ma/L €0 1 on i e s 1 m 1 S o l i d s . mu/L

7/23/87 Recycled Coolant 2 .o 2,000 1 30,000,000 41

9/22/87 Recycled Coolant 10 37,000 74,800,000 470


NOTES: 1 ) Machine No. 1720 is an Okuma unit and runs stainless steel and aluminum parts (pods) using Blasocut 2000.

2) Refractometer readings were made using an American Optical hand-held refractometer, Model No. 10440. Readings were corrected according to the calibration curve shown in FIgure I.

3 ) I'mg/L" means milligrams per liter of coolant.

-1 4-

TABLE 11-F

MACHINE NO. 1714 COOLANT ORGANIC COMPOUND SCAN RESULTS



Concentrat 1 on 7-23-87 9-23-87 10-15-87 mu!! Unlts MDL

Methanol x Ethanol x Methylene ch lor ide x Ace tone x Isopropyl alcohol x n-Propanol x t-Bu tanol x Tetrahydrofuran x Chloroform x 1 , l ,2-Trichloro 1,2,2,- %

Methyl e thy l ketone x 2-Butanol x l , l , l -Tr ich loroethane x Ethyl acetate x l , l ,Z-Trichloroethane x n-Bu tano 1 x Benzene r Hexane x Cyclohexanone x Methyl isobuty l ketone X l , l ,Z,Z-tetrachloro- x Butyl acetate x Heptane x To1 uene x Ethyl benzene x Xylenes x Total unknown peaks x

t r i f luoroe thane

ethylene

High b o i l i n g compounds %

0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1

0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1

0.1 0.1 0.1 0.1 0.1 0.1 0.1

NO ND NO NO ND ND ND NO NO NO

NO ND ND ND ND ND ND NO ND ND ND


ND ND ND ND ND ND NO NO ND NO

ND ND ND ND ND ND ND ND ND ND NO

ND ND ND ND ND ND NO 1

ND ND NO ND ND ND NO ND ND ND

ND ND ND NO ND ND ND ND ND ND ND

ND NO ND ND ND ND 7k0.3

NOTES: "MDL" means analy t ica l method detect ion 1 i m i t "ND" means not detected a t or above MDL

-1 5-

TABLE 11-G

Sampl i ng Date Loca t 1 on

ORGANIC VAPOR SAMPLING RESULTS WASTE MANAGEMENT BUILDING



Sampl i ng Concentration, Period E A w 2

7/24/87 5 ft. from S. Wall 141 0-1 552 <o. 01 <o. 02 20 ft. from W. Wall 5.5 ft. height

9/22/87 5 ft. from S. Wall 151 5-1 654 0.08 0.07 20 ft. from W. Wall 5.5 ft. height

OSHA Permissible Exposure Limits (PEL'S): 3 50 500 ACGIH Threshold Limit Values (TLV's): 350 100

NOTES: 1 ) Samples were collected by PACE Laboratories, Inc.(PACE> personnel.

2 ) "ppm" means parts per milllon.

3 ) Chemical abbreviations: l,l,l-Trichloroethane (TCA) Methylene Chloride (MeC12)

4) "<"means less than stated value (airborne detection limit)

5) No air sample was collected on 10-15-87.

-1 6-

Appendix C

Monitoring and A n a l y s i s - I1

111. ANALYTICAL RESULTS AND OBSERVATIONS

December 1987 through January 1988

Samples o f Blasocut 2000 coolant from five machine tools were evaluated for percent coolant, oil and grease, total bacteria plate count and suspended solids. The unit for coolant concentration is percent (%). The unit for oil and grease and total suspended solids is milligrams per liter of coolant (mg/L>. Total bacteria plate count results are reported in (bacterial) colonies per milliliter (ml) of coolant.

The results for each of these parameters is shown for the last two sampling events performed o n December 17, 1987 and January 22, 1988. A separate table presents data for each of the five machine tools evaluated. The results of previous sampling events are shown in Section 11.

A s shown in Tables 11-A through 11-E and 111-A through 111-E, the oil and grease concentrations appear t o have increased significantly from July 1987 to January 1988. The results of coolant analysis o n samples collected in January 1988 indicated a decrease in oil and grease concentrations when compared to results from.0ctober and December, 1987.

The most significant reduction in oil and grease concentrations was observed for Machine No. 3806. The measured oil and grease concentrations on the recycled coolant sample collected o n January 22, 1988 was 12,000 mg/L compared t o a high of 49,000 mg/L measured in October, 1987. In November of 1987, a proprietary belt-type oil skimmer was installed at Machine No. 3806 (Master Chemical Corporation "Scrounger" brand oil skimmer). The use of this o i l skimmer appears to have been accompanied by a significant decrease in the oil and grease concentration and a similar decrease in total suspended solids.

Percent coolant concentrations remained relatively steady throughout the survey. Only the recycled coolant from Machine No. 1720 showed a general increase In coolant concentrations from July, 1987 t o January, 1988, with wide fluctuations. All o f the percent coolant measurements were well within the stable coolant range, as shown in Figure I.

Total bacteria plate count results tended to increase with successive sampling events. The results, however, are in the range that is expected, according to available literature o n water-soluble cutting fluids.

The total suspended solids results increased for several of the machine tools evaluated, with a decrease noted for most of the machine tools between the December and January sampling events. The most significant decrease, as discussed above, was for Machine No. 3806.

- 1 7-

Results of informal interviews conducted with machine operators did not reveal any work-related skin disorders since using the recycled Blasocut 2000. Photographs were taken in January, 1988 to document the condition o f machinists hands after seven months of handling recycled coolant. No changes were noted in comparing baseline photographs with photographs taken on January 22, 1988.

The results o f air sampling in the waste management building were well below the respective OHSA Permissible Exposure Limits for 1 , l ,I-trichloroethane and methylene chlorlde. Most of the air sampling results were below the analytical detection limit for these compounds.

-18-

TABLE 111-A




Total Total Refractometer O i 1 and Bacteria Suspended

Sampl 1 ng Reading, Grease, Plate Count, Sol i d s , Date Des cr i o t i on X Coolant ma/L Colonies/ml ma/L

12/17/87 Recycled Coolant 4.5 31,000 1 60,000,000 1,500

1 1 /22/88 Recycled Coolant 6.0 14,200 130,000,000 6 90

NOTES: 1 ) Machine No. 1723 Is a Mori-Seiki unit and runs ferrous metal parts using Blasocut 2000.

2) Refractometer readings were made using an American Optical hand-held refractometer, Model No. 10440. Readings were corrected according to the Calibration curve shown in Figure I.

3 ) "mg/L" means milligrams per liter of coolant.

4) "ml" means mi 1 1 i 1 1 ters o f coolant

- 1 9-

TABLE 111-B



HASHINGTON S C I E N T I F I C INDUSTRIES, INC. LONG LAKE, MN

Total Total Refractometer Oil and Bacteria Suspended

Sampl i ng Reading, Grease, Plate Count, Sol ids, Oate - Descr 1 pt 1 on x coo lant ma/L Colonies/ml mg/L



NOTES: 1 ) Machine No. 1714 i s a Hitachi-Seiki unit and runs low carbon steel and copper parts using Blasocut 2000.

2) Refractometer Readings were made using an American Optical hand-held refractometer, Model No. 10440. Readings were corrected according t o the calibration curve shown in Figure I.

3) "mg/L" means m i 1 1 Igrams per 1 iter o f coolant.

4) " m l " means milliliters o f coolant.

5) The coolant I n Machine 1714 was last changed in June, 1987.

-20-

TABLE 111-C



HASHINGTON SCIENTIFIC INDUSTRIES, INC. LONG LAKE, MN


Sampl i ng Reading, Grease, Plate Count, Sol ids, Date DescrlDfim % Coolant ma/L Col on i e s /ml ma/L

12/17/87 Recycled Coolant 4.5 36,000 64,000,000 7 50


NOTES: 1 )

2 )

3)

4 )

5)

Machine No. 3806 i s an Ohio Broach and Tool unit and runs aluminum parts using Blasocut 2000.

Refractometer readings were made using an American Optical hand-held refractometer, Model No. 10440. Readings were corrected according to the calibration curve shown In Figure I.

Ifmg/Llf means mi 1 1 i grams per 1 1 ter o f cool ant.

"ml" means milliliters of coolant.

Fresh coolant was added to Machine 3806 on September 21, 1987.

-21-

TABLE 111-D



HASHINGTON S C I E N T I F I C INDUSTRIES, INC. LONG LAKE, MN


Sampl i ng Reading, Grease, Plate Count, Sol ids, Date Description 7. Coolant ms/L Col on i e s /ml ma/L

12/17/87 Recycled Coolant 1 1 47,000 252,000,000 3,100

1 /22 /88 Recycled Cool ant 10 20,500 310,000,000 1,400

NOTES: 1 ) Machine No. 4719 is a Niigata unit and runs aluminum parts using 81 asocut 2000.

2) Refractometer readings were made using an American Optical hand-held refractometer, Model No. 10440. Readings were corrected according to the calibration curve shown In Figure I.

3 ) "mg/L" means milligrams per llter of coolant.

4) "ml" means milliliters o f coolant.

-22-

TABLE 111-E



HASHINGTON SCIENTIFIC INDUSTRIES, INC. LONG LAKE, MN

Tota l Tota l Refractometer 011 and Bacter ia Suspended

Sampl 1 ng Reading, Grease, P la te Count, So l l ds , Date Descr lDt lon x coo l a n t mu/ L Colonies/ml mu/L

12/17/87 Recycled Cool a n t 16 72,000 1 50,000,000 1,400

1/22/88 Recycled Coolant 13 39,000 1 67,000,000 1 ,100

NOTES: 1 ) Machine No. 1720 i s an Okuma u n i t and runs s ta in less s t e e l and aluminum p a r t s (pods) us ing Blasocut 2000.

2) Refractometer readings were made us ing an American Op t i ca l hand-held re f rac tomete r , Model No. 10440. Readlngs were cor rec ted according to the c a l i b r a t i o n curve shown i n F igure I.

9ng/L" means m i l l i g r a m s per l i t e r o f coo lan t . 3 )

4) "ml" means m i l l i l i t e r s o f coo lan t .

-23-

TABLE 111-F

Parameter

Methanol Ethanol Methylene chloride Acetone Isopropyl alcohol n-Propanol t -Bu tan0 1 Tetrahydrofuran Chloroform 1,1,2-Trichloro-1,2,2,-

trifluoroethane Methyl ethyl ketone 2-Butanol 1 , l ,I-Trichloroethane Ethyl acetate 1 , l ,Z-Trfchloroethane n-Bu t ano 1 Benzene Hexane Cyclohexanone Methyl isobutyl ketone 1,1,2,2-tetrachloro-

ethylene Butyl acetate Heptane To1 uene Ethyl benzene Xylenes Total unknown peaks

MACHINE NO. 1714 COOLANT PACE PROJECT NO. 870611.361


uus - MD L

%

1. % x x x x x x x x x

0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1

0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1

0.1 0.1 0.1 0.1 0.1 0.1

Concentrat ion 1/17/87 1/22/88


ND ND ND ND ND ND NO NO NO ND ND

NO ND NO ND NO NO

ND ND ND ND ND ND ND ND NO ND

ND ND NO ND ND ND ND ND ND NO ND

ND ND ND NO ND ND

NOTES: "MDL" means analytical method detection 1 Imi t "ND" means not detected at or above MDL

-24-

TABLE 111-G

ORGANIC VAPOR SAMPLING RESULTS HASTE MANAGEMENT BUILDING



Samples Co l lec ted on January 9, 1987 - Sampl i ng Sampl i ng

Date Locat i on Per iod m w12-

12/17/87 On S. wa l l 1411-1527 <o. 01 <O. 03 20 ft. f rom W. wa l l 6 f t. he igh t

1 /22/88 On S. wa l l 1422-1 556 <o .02 <O. 03 20 ft. from W. wa l l 6 ft. he igh t

OSHA Permiss ib le Exposure L i m i t s (PEL'S): 350 500 ACGIH Threshold L i m i t Values (TLV's): 350 100

NOTES: 1 ) Samples were c o l l e c t e d by PACE Labora tor ies , I n c . (PACE) personnel .

2 ) "ppm" means p a r t s per m i l l i o n

3 ) Chemical abbrev ia t ions : l , l , l -T r i ch lo roe thane (TCA) Methylene Chlor ide (MeC12)

4) means below s ta ted value ( a i r b o r n e d e t e c t i o n l l m i t ) .

-25-

Appendix D

Conclusions and Recommendations

I V . CONCLUSIONS AND RECOMMENDATIONS

Recycled Coolant Oua l i t y - A s was discussed i n Sect ions I 1 and 111, the percent coo lan t remained i n the s tab le range, accord ing t o f i g u r e I, attached. The f l u c t u a t i o n s i n percent coo lan t throughout the p r o j e c t w e r e no t s i g n i f i c a n t . The measured percent coo lan t values i n some o f the machine too l s were c o n s i s t e n t l y h igher . This d i f f e r e n c e between d i f f e r e n t machines, however, was no t associated w i t h any s i g n i f i c a n t d i f f e rences i n the o ther parameters.

I n genera l , the o i l and grease concent ra t ions increased f o r m o s t o f the machines evaluated. The o i l and grease concent ra t ions appear t o be manageable i n t h a t s i g n i f i c a n t reduct ions were noted f o r Machine No. 3806 wh i le us ing a Scroctnger brand motor ized be l t - t ype skimmer. The skimmer appears t o be adaptable for use a t the source. Un fo r tuna te l y , the e f fec t i veness of the sk immer was o n l y evaluated a t Machine No. 3806 d u r i n g t h i s survey. A por tab le skimmer connected t o a waste o i l drum was be ing i nves t i ga ted , bu t was n o t i n use as o f January, 1988.

To ta l b a c t e r i a p l a t e count r e s u l t s appeared t o increase throughout the p r o j e c t . Most o f the b a c t e r i a counts s t a b i l i z e d i n the range o f one hundred and f i f t y m i l l i o n (150,000,000> co lon ies per m i l l i l i t e r of coo lan t . Where o i l and grease concent ra t ion reduc t ions were observed, increases i n t o t a l bac te r ia p l a t e count were o f t e n observed. A r e d u c t i o n i n o i l and grease concentrat ions favo rs aerobic cond i t ions , thus reduc ing the p r o b a b i l i ty t h a t fungal agents o r anaerobic microorganisms may be present . A s was discussed i n Sect ion I , anaerobic b a c t e r i a and fung i a re associated w i t h the produc t ion o f hydrogen s u l f i d e ( H 2 S > , which i s o f t e n descr ibed as a " r o t t e n egg" odor. Dur ing normal ope ra t i on , none of the machines were assoc ia ted w i th an ob jec t ionab le odor. Several machin is ts noted t h a t machines which had n o t been used for over f o r t y e i g h t (48) hours o f t e n d i d produce an o b j e c t i o n a b l e odor, due t o the f a c t t h a t t he coo lan t was no t adequately aerated as i t would be du r ing normal operat ion.

To ta l suspended s o l i d concentrat ions increased, o v e r a l l . Some reduct ions i n t o t a l suspended s o l i d s were observed, such as i n the case o f Machine No. 3806, which was equipped w i t h a motor ized b e l t - t y p e skimmer. I n a d d i t i o n t o reduc ing the o i l and grease concen t ra t i on i n the recyc led coolant a t t h l s machine, t he skimmer was a l s o ab le t o remove a s i g n i f i c a n t percentage o f metal ch ips and o t h e r so l i ds . I t was be l i eved t h a t a d d i t i o n a l reduct ions i n t o t a l suspended s o l i d concentrat ions cou ld be achieved through the use o f a c e n t r i f u g e . Pre l im inary t e s t s us ing a c e n t r i f u g e w e r e performed by Washington S c i e n t i f i c I n d u s t r i e s for severa l months, b u t met w i t h l i m i t e d success. No a d d i t i o n a l t e s t i n g us ing the c e n t r i f u g e i s planned.

m u p a t i o n a l Heal th Considerat ions - Dermal E x ~ o s u ~ - Informal in terv iews conducted w i t h machin is ts ope ra t i ng a l l of t he machine t o o l s evaluated dur ing t h i s p r o j e c t repor ted t h a t they exper ienced no s k i n d isorders dur ing the p e r i o d from Ju ly , 1987 through January, 1988. One i n d i v i d u a l had repor ted

-26-

experiencing boils. This particular skin disorder, however, existed before the inception of the coolant recycling project. The origin of this particular problem has not been determined.

Comparison of baseline photographs of machinists and forearms with photographs taken o n January 22, 1988 yielded n o observable changes.

Based on these observations, the use of recycled Blasocut 2000 coolant does not appear to be associated with any increase in adverse skin conditions or dermatitis. Most o f the machinists interviewed worked at several different machines, but used Blasocut 2000 most o r all of the time that they were operating machine tools.

The only history of dermatitis reported by the machinists interviewed pre-dated the use of Blasocut 2000 and was usually associated with oil-based (non-water soluble) metal working fluids. Some oil-based cutting fluids are still i n use, t o a lesser degree. Dermal exposure to oil-based cutting fluids and to oil and grease which has accumulated in water soluble cutting fluids could potentially produce an acne-type dermatitis known as folliculitis. Control of the oil and grease concentrations in the recycled coolant will minimize the possibility of machinists developing this type of skin disorder. Frequent washing of the hands and forearms was practiced by most of the machinists interviewed. It is not believed that protective gloves are necessary when using water-soluble coolants, but they would further reduce the possi bi 1 i ty of dermatitis.

Other potential skin irritants, besides the presence of o i l s and greases, include bacteria, fungi and metal particulates. The presence of bacteria in the water soluble coolants does not, in itself, indicate a significant problem. A s has been indicated before, greater than ninety-nine percent (99%) of the aerobic bacteria present in well-aerated coolants are non-pathogenic. The presence of bacteria in the concentrations shown in the attached tables should not produce any adverse health effects. These concentrations o f aerobic bacteria compete with fungal populations and populations of anaerobic bacteria, both of which are associated with the production of objectionable odors and which may produce bacterlal o r fungal infections. Although the bacteria present in the recycled coolants i s believed t o be non-pathogenic, adequate personal hygiene must be maintained to prevent accidental fngestion of these bacteria.

The operations in the waste management building are believed t o require the use of protective gloves which are impervious to solvents and oils. The use o f gloves i s necessary because o f the need t o handle more non-water soluble oils, waste oils, and waste solvents, such as 1 , l ,I-trichloroethane and me thy 1 ene chlor i de.

Q c c u p a t o n a l Health ConJiderations - Inkalation ExDosure - During normal machining operations, n o significant misting of the cutting fluids was observed. Since no OSHA o r NIOSH validated sampling method exists for

-27-

water-soluble cutting fluids, the mist concentrations were not evaluated. Most of the mist which i s generated i s trapped and recovered in the machine tool, itself, since the machine door is closed during machining. The concentrations of insoluble oil in the recycled coolant are generally below four percent ( 4 % > , by weight. Since the OSHA Permissable Exposure Limi3 (PEL) for o i l mist exposure i s five milligrams per cubic meter of air (mg/m >, the total mist exposure would have to be in excess of 100 mg/m3. Airborne mist concentrations o f 5 mg/m3 usually produce vi s i ble emissions, based on the experience o f the investigator. No oil mist was visible outside of the machine tools, thus, oil mist exposures are not believed t o be detectable In air.

The operations performed in the waste management building are not believed to produce any significant misting of oil. The only measured airborne contaminants were l,l,l-trichloroethane, methylene chloride and 1,1,2-trichloro-1,2,2,-trifluoroethane (Freon 1131, as shown in I-E, 11-G and 1 1 1 - G . The highest concentrations for any of the compounds documented in the waste management building represent approximately 0.2% of the PEL for the compounds evaluated.

ua-ste Coolant TretltmxnL - A1 though Blasocut 2000 water-soluble metal working fluid was successfully recycled for a period o f over seven months, ultimately, some coolant waste i s inevitable. Enclosed in Appendix A are results of an evaluation of four treatment protocols for water-soluble coolant waste.

As is discussed in the attached Appendix, these protocols were successful in reducing the oil and grease concentrations of the waste coolant. Oil and grease and other specific parameters were evaluated before and after treatment and are presented in the attached report. Oil and grease was the only parameter which was significantly reduced by treatment. However, all of the relevant parameter results were below the applicable dlscharge limits, based o n past monitoring reports and assuming a daily discharge o f 100 gallons o f treated coolant. The actual daily discharge of treated Blasocut 2000 has not been determined, but i s expected to be far below 100 gallons.

-28-

C o r r s c t i o n t ab le t o determifie concentracion r e a d i n g w i t h r e f r ac to - meter . The s c a l e is based on measuring temperature o f 20' C o r 68" F.

A t I I 1

Reading

32 f ra c tone t e K

Scale

90

80

7a

60

50

40

30

20

10

0

s U lq I

0 10 20 30 40 5il SO 70 80 90 100

Concentrat ion i n X

S = S t a b l e range of emulsion U = Unstable range of emulsion

Note: I n the tan2e o i 60 ai:d $ 5 :: cancenccacion a d o ~ ~ b l + r e f r a c t .- can be de t ec t ed .

I F I G U R E I REFRACTOMETER C A L I B R A T I O N CHART

BLASOCUT 2000 'ln

Appendix E

T r e a t a b i 1 i t y

Fer= laboratories, inc.

Offices: Minneapolis, Minnesota Tampa, Florida Coralville, Iowa

1710 Douglas Drive North 0 Minneapolis, M N 55422 0 Phone (612) 544-5543 0 FAX (612) 544-3974

March 1 1 , 1988

Mr. Joseph Pallansch Washington Scientific Industries, Inc. 2605 West Wayzata Boulevard P.O. Box 340 Long Lake, MN 55356

Re: Sewer Discharge of Used Machining Coolant PACE Project No. 880119.200

Dear Mr. Pallansch:

We are writing to provide results of treatability tests performed on a sample of your waste water-soluble coolant. The tests were performed to evaluate the effectiveness of several treatment methods based on the wastewater discharge limitations applicable at your Long Lake, Minnesota facility. This letter will descrlbe each treatment method, present the results of treatment and recommend di sposal procedures.

Treatment Methods

Four treatment methods were tested for their ability to reduce oil and grease, chemical oxygen demand and metals from a coolant sample. Each treatment was performed from a portion of the same coolant sample. Table 1 provides a descrlptlon o f the treatment procedures studled. After oil removal, the treated samples were analyzed for metals, oil and grease and total suspended sol ids.

Analytical results of the treatment study are shown In the laboratory report provided as Attachment A . sample as well as each treated solution. untreated sample contained high concentratlons of chemical oxygen demand, biochemical oxygen demand, 011 and grease and total suspended solids. In add1 tion, the untreated sample contained copper and zinc at levels above Federal Metal Finishing discharge limitations.

The results characterize the untreated The results show that the

Results of the treated samples show that metals concentratlons remained above Metal Finishing limitations i n all of the samples. Although poor metals removal was obtained the treatment methods can be compared I n terms of 01 1 and grease removal. As shown on the laboratory report the best reduction in 0 1 1 and grease was found in the Alum and Calcium treated samples. Please note that the Calcium treatment method Is much simpler than the Alum method.

PACE Laboratories, Inc. March 1 1 , 1988

- 2 -

Mr. Joseph Pallansch Washington Scientific Industries, Inc.

fac 1 lltv D ischarue C - Based on the poor metals treatment results faci 1 i ty discharge moni toring reports were reviewed to determine i f the waste coolant would be suitable for sewer discharge. From the monitoring Information you supplied an average process discharge volume and average metals concentrations were used t o calculate the addition of 100 gallons o f waste coolant to the dally discharge. From this calculation the composite discharge metals concentrations were well within MWCC and Federal Metal Finishing limitations. Also we d o not expect a significant increase In strength charge associated with an infrequent discharge o f 100 gallons of the waste coolant.

Summary and RecQmmendatio ns

The treatment methods investigated were ineffective in removing regulated metals from the waste coolant. However, based o n a review of facility discharge monitoring reports a daily discharge of approximately 100 gallons would be suitable for sewer discharge. waste coolant i s discharged to the sewer after removal of metal fines and oil separation. Gravity oil separation would be adequate for sewer discharge, however, the calcium treatment method could be used to enhance oil removal.

We recommend that the

If you have any questions concerning this report, please do not hesitate t o contact me.

Sincerely,

, t -, ~ , ~ ~ - ;; f ; d - L L # 4 d , -. James A . Postlgllone, P.E. Project Engineer

JAPI j b

-3 1-

TABLE 1

DESCRIPTION OF TREATMENT PROCEDURES WASHINGTON SCIENTIFIC INC. WASTE COOLANT TREATMENT

March 1 1 , 1988 PACE Laboratories, Inc. Iron -- Tr e a tme n t

Acid Step Treatmmt

Alum Treatment

Cal c 1 um - Tr ea tmeni

1 Add sulfuric acid unti 1 a pH between 3 to 4 is reached; approx 1 ma t e 1 y 0.4 gallons per 100 gallons of waste coolant.

Add sulfuric acid unti 1 a pH between 3 to 4 is reached, approximately 0.4 gallons per 100 gallons o f waste cool ant .

Add approxlmately 1.5 pounds of calcium chloride per 100 gallons of waste coolant.

Add approximately 1.2 pounds of ferrous hydroxide ammonium sulfate per 100 gallons of waste coolant.

A1 1 o w approx 1 mat e 1 y 2 hours for gravity oil separation.

Mix for 30 minutes. Mix for 15 to 30 minutes.

2 Add approximately 0.15 pounds of aluminum sulfate per 100 gallons of waste coolant.

Allow approxlmately Add sulfuric acid 2 hours for gravity until a pH below 01 1 separation 5 i s reached;

approximately 0.15 gallons per 100 gallons of waste coolant.

Mix for 30 minutes Skim off oil 3

Allow approxlmately Drain supernatent Skim off otl. 2 hours for gravity oil separation.

to sewer. Ralse pH with lime; approximately 1.8 pounds per 100 gallons o f waste coolant.

4

5 Skim of f oil Drain supernatent A1 1 on approx i - to sewer. mately 2 hours

for gravity oi 1 separation

6 Add sodium hydroxlde t o raise pH t o 7: approxtmately 0.7 pounds per 100 gallons of waste coolant.

Skim off oil.

7 Drain supernatent t o sewer.

Drain supernatent to sewer.

-32-

ATTACHMENT A

REPORT OF LABORATORY ANALYSIS

-33-

Offices: REPORT OF LABORATORY ANALYSIS Minneapolis. Minnesota

Tampa, Florida Coralville, Iowa

Washington S c i e n t i f i c I n d u s t r i e s , Inc. March 11, 1988 2605 Wes t Wayzata Blvd. P.O. Box 340 Long Lake, MN 55356

A t t n : M r . Joe Pal lansch

D a t e Sample(s) Col lec ted : 02/08/88 D a t e Sample(s) Received: 02/08/88

PACE Sample Number:

- Paramete r

Blochemtcal Oxygen Demand Chemical Oxygen Demand Chroml um Copper Lead

N i cke 1 011 and Grease Sol Ids , Total Suspended Zinc

PACE P ro jec t Number: 880208506

MD L Method De tec t i on L l m i t ND Not detected a t or above the MOL.

Unlts

mg/L mg/L mg/L mg/L mg/L

mg/L mg/L mg/L mg/L

mL_

60 50 0.05 0.01 0.1

0.05 1 1 0.10

029420 029430 029440 Coolant A c i d Alum. Mach. Treated Treated N o . 7 1 4 Coolant :oolantL-

2 5000 - - 31 500 - - 0.35 0.12 0.16 6.7 5 . 5 5 . 5 0.1 0.3 0.4

NO 0.10 0.22 3800 480 200 1600 150 130 34 29 31

-34- 1710 Douglar Drive North a Minneapolis, MN 55422 0 Phone (612) 544-5543 ._ ..

Off ices: REPORT OF LABORATORY ANALYSIS Minneapolis. Minnesota Tampa, Florida Coralville, Iowa

Mr. Joe Pallansch Page 2

PACE Sample Number:

Parameter

Chemical Oxygen Demand Chromium Copper Lead Nickel

011 and Grease Solids, Total Suspended Zi nc

March 1 1 , 1988 PACE Project Mumber: 880208506

029450 029460 Calcium Iron Treated Treated

!+hi& MDL coo 1 ant Cool ant

mg /L 50 - 15400 mg/L 0.05 0.18 0.07 mg/L 0.01 3.4 2.5 mg/L 0.1 1.5 0.3 mg/L 0.05 0.43 0.14

mg/L 1 2 60 370 mg/L 1 880 510 mg/L 0.10 9.8 8.3

MD L Method Detection Limit

The data contained in thts report were obtatned ustng EPA or other approved methodologies. All analysis were performed by me or under my direct supervision.

Thomas L. Halverson Inorganic Chemlstry Manager

-35- 1710 Douglas Drivo North 0 Mlnneapoih, MN 55422 0 Phone (612) 544-5543

PROJECT SUMMARY

Machine Coolant Waste Reduction by Optimizing Coolant Life

Joseph Pallansch

Machine shops use coolants to improve the life and function of machine tools. These coolants become contaminated with oils with use, and this contamination can lead to growth of anaerobic bacteria and shortened coolant life. This project investigated methods to extend coolant life through improved coolant maintenance, with the goal of reduced volumes of coolant waste.

Skimmers to remove oil from the surface of coolants were found to be cost-effective. Use of a centrifuge was also tested. Coolant change practices were documented, and modified for improved coolant life. A specific coolant with wide applicability and tolerance was tested and found to have a life of at least seven months using the documented procedures.

Introduction

Machine shops use coolants to transfer heat generated during the machining process away from cutting tools and parts being produced. The coolant is collected in and recirculated from a sump. During use the coolant collects oil from the machining process. This oil, called tramp oil, contributes to the growth of anaerobic bacteria, which produce hydrogen sulfide gas, shorten coolant life, and eventually force disposal of the coolant as waste.

Coolant sumps contain from 20 to 100 gallons each and, depending on maintenance practices, the coolant may require monthly or even weekly replacement. Even a small shop will have several machine tools, and large shops can have 100 and more. The exact management scheme for this waste coolant is determined b y the type of coolant, level of contamination, presence of regulated materials (metals, organic solvents) and availability of treatment. Disposal costs vary from $20 to $200 per 55-gallon drum depending on management required.

Washington Scientific Industries (WSI) is a machine shop which uses a wide variety of tools to make parts from materials such as steel, aluminum, copper, and stainless steel. The machines used are medium-sized and are similar to those used in many machine shops. The volume of waste coolant generated by WSI is affected by business activity, but averages 120 55-gallon drums per year with a management cost of $140 per drum.

This project was designed to study the following:

o A specific water-soluble coolant (Blasocut 2000 Universal) in use with a variety of machines, tools, and materials.

o Coolant maintenance practices associated with three types of machines

o Health effects of use and handling of recycled coolant o Handling practices for chips and waste coolant o Chip/coolant separation o Oil/water separation

The goal is to identify factors and techniques which contribute to the extension of coolant life, and to document procedures and effects of the entire coolant life cycle. This information should be useful for decision-making by other shops attempting to reduce the volume of waste coolant generated.

Procedures

The coolant chosen for the project, Blasocut 2000 is a mineral oil based, water-soluble metal-working fluid. It is intended for use with all chip-forming operations except grinding and all materials except magnesium. The concentrate is made up of 60% refined mineral oils, to which emulsifiers and corrosion inhibitors are added. No biocides are present in the concentrate, nor are any required for maintenance of the solution. Company literature indicates that use of this coolant does not adversely affect worker health, and that the coolant is recycled extensively in other applications.

Machines chosen for the project are one to four years old and used for jobs with long (2-4 weeks) production runs. Operators, material and process were held constant during the project as much as possible. Standard industrial engineering practices were used to determine direct and indirect labor required for coolant change practices, coolant maintenance, waste handling, and waste containment.

Sampling was done to establish baselines for new coolant, way oil, coolant dilution water, air quality, and health effects. Ongoing sampling and analysis was also performed to monitor recycled coolant quality, air quality, and health effects. A l l sampling and analysis was performed by an independent consulting laboratory.

After several months of characterization, various coolant maintenance practices were evaluated. These included disk and belt skimmers for removing tramp oil, a centrifuge for removing tramp oil, and coolant change and sump cleaning practices. Sump modifications were required in order to mount equipment on the control group of machines, and additional equipment such as timers and coolant circulating pumps were also evaluated.

Chip handling practices from generation to storage prior to salvage were evaluated in order to address the problems of inefficient handling, poor salvage quality, and escape of coolant and oil draining from chips in storage. Time-and-motion studies were used to develop an efficient system for moving chips from the machine tools where they are generated to a waste mangement building specifically designed to capture and store draining coolant and oil and protect chips while in storage.

Results and Discussion

The following change practice was established as the most efficient for extended coolant life.

1) Skim all tramp oil from coolant surface 2) Pump coolant from sump 3) Vacuum chips from sump 4) Remove sump access covers 5 ) Vacuum chips from sump 6) Steam clean and vacuum sump (repeat until clean) 7 ) Replace sump access covers 8) Replace coolant

The new change practice requires an average of 5.21 hours to accomplish on a cast sump. Sumps made of sheet metal take several hours less because corners are more easily cleaned. This new coolant change practice, when combined with improved ongoing coolant maintenance, holds promise for extending coolant life.

Both belt and disc-type skimmers effectively reduced coolant oil and grease concentrations. This increases aerobic activity in the coolant, contributing to longer coolant life. A centrifuge was evaluated for cleaning the coolant in the sumps of 25 machines not in the study group, and found to not be cost- effective, at least in a mobile configuration.

Blasocut 2000, even after being recycled for seven months, meets or exceeds metal removal rates for aluminum, steel, copper and stainless steel. The use of recycled coolant also does not appear to be associated with any increase in dermatitis on operator’s hands. Lab research showed that when the recycled coolant must be disposed, an oil/water separation can be accomplished by acidifying the coolant and allowing the oil fraction to separate. Elevated levels (2.5-3.5 mg/l copper; 8-10 mg/l zinc) of copper and zinc were found in the water fraction of the coolant left after this separation.

Conclusions

The results of tests conducted during this project indicate that it is possible to extend the life of machine tool coolant significantly and thereby reduce the volume of waste coolant generated.

It seems important to use a coolant and way oil with wide applicability and suitability for recycling. Key factors seem to be tolerance of hard water, resistance to anaerobic bacteria growth, and stability over a range of concentrations.

The project found that simple skimming of tramp oil using any of several different methods was cost-effective and reduced oil and grease concentration significantly. This proved sufficient to extend coolant life'to at least seven months, where previously used coolant may have been changed after one week.

Recommendations

While use of a single coolant is proving possible for 90% of the requirements of WSI, many machine shops will balk at changing their coolants. Further research is needed on the coolant maintenance and change practices documented in this project and their effect on the life of a variety of coolants. Research is also needed on alternate cooling methods and schemes for preventing contamination of coolant by way and hydraulic oil.

Machine Coolant Waste Reduction By Optimizing Coolant Life

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