[PPT]PowerPoint Presentation - Ohioweb.epa.ohio.gov/opp/Metal Finishing Training Web.ppt · Web viewMetal Finishing (Electroplating) P2 Workshop Part 1 Ohio EPA Division of Hazardous

Metal Finishing (Electroplating)

P2 Workshop

Part 1

Ohio EPA

Division of Hazardous Waste Management

Office of Pollution Prevention

Good morning, welcome to the Metal Finishing Sector Pollution Prevention Workshop

Whats in it for Me?

Understanding of Metal Finishing Unit ProcessesSkills for Identifying Process Optimization (P2!) OpportunitiesKnowledge of Tools and Resources for Providing Technical Assistance

Value of this training. This training should make you more comfortable in identifying potential pollution prevention opportunities at metal finishers and coaters that you inspect. We hope to give a broad but accurate overview of plating processes and situations that you may encounter. Each section will have some basic keys to look for when visiting a plating facility. We want you to be confident in suggesting options for facilities to pursue and know where to find resources and assistance should a facility be open to considering P2 opportunities.

Metal Finishing Process Unit

9

This is a very basic input output diagram to begin to consider opportunities for reductions in raw materials and subsequent waste streams.

Metal Finishing Processes

Surface Preparation and Cleaning:

alkaline cleaning

electropolishing

oxide removal

Metal Plating:

electroplating

electroless plating

Protection and Finishing Treatments:

anodizing

chromate conversion

phosphating

Basic metal finishing process usually incorporate these 3 major steps

Some type of cleaning and preparation step, in order to allow the work piece to accept a coating. The coating or Plating process where metal ions are attached to the surface by a bond Some sort of protective coating to seal the finish

Surface preparation will usually start with removal of fluids from machining and or shipping protective coatings. This step should be the beginning of the P2 focus at a facility. Carry over from the cleaning or preparation phase will impact the plating solution and possibly subsequent rinses.

Alkaline cleaning: oil, dirt, coating removal

Electropolishing: reverse plating process, remove thin coating of metal from part, shiny surface (from which the name is taken)

Oxide removal: acid stripping of rust also done for surface preparation, longer is pickling.

Electroplating is the electronic deposition of a metal ion on the surface of a negatively charged work piece.

Electroless plating is the same deposition process except current is not used, a solution of metal ions still deposits on the work piece.

Anodizing: this process is basically the same as electropolishing except the purpose is to form a thin oxide on the surface of the part.

Chromate Conversion Coating: this process uses chromic acid to form a thin gel like film of chromic oxide and aluminum oxide on the part surface. This is frequently used so that paint or adhesives will adhere to aluminum parts.

Phosphating: a thin layer of phosphate crystals on the metal surface, for coating adhesion.

Typical Plating Line

Slide 17

Plating Line/Department Except for vapor degreasing, which normally is performed off-line, plating operations are normally incorporated into a sequence of tanks, called a "line."

A plating line may be designed to produce a single coating or a number of coatings. While not always the case, the process line contains tanks lined up in sequential order. Automated lines may or may not contain tanks in sequential order.

A zinc plating line may therefore consist of 13 tanks, each containing a chemical processing solution or rinse water, soak clean, electroclean, rinse, acid, rinse, zinc plate, rinse, bright dip, rinse, chromate, rinse, hot water rinse, and dry. If the line is for barrel plating, each tank may have one or more "stations," that is, places to put a barrel. A six-station zinc plating tank can plate six barrel-loads of parts at one time. To economize, some shops may have one cleaning line that services several plating lines. There also are tanks for rack stripping, stripping rejects, purifying contaminated solutions or holding solutions that are only sporadically used. The entire lineup of tanks and lines creates a "layout" of the shop, with parts entering the plating department from one direction, traveling through the process lines, and leaving the plating department.

Common Metal Finishing Wastes

Rinse water effluentSpent plating baths Spent alkaline and acidic etchants and cleanersSpent strippersSolvent degreasersWaste and process bath treatment sludgesMiscellaneous wastes (filters, empty containers, floor grates, off-spec chemicals)

* Some of these may be Persistent Bio-accumulative Toxic substances such as Cadmium, Chromium, Copper, Lead, Nickel, Zinc & Cyanide

Rinse water effluent receives metals loading, cleaners, etchants and often requires pH adjustment. Volume of the waste water is a key, along with any alternative chemistries for cleaning, coating, etc. Always ask if a process step is required by the customer, or if alternatives would be acceptable.

P2 Principles for Metal Finishing

Use the least toxic/easiest to manage chemicals

Extract the most life (use) out of process chemistries

Keep process chemistry solutions where they belong: in the tanks

Return as much escaping solution (dragout) as possible to the tanks

Use the least amount of rinse water required for good rinsing

28

Least toxic chemicals, starting with coolants fluids or lubes if parts are machined, then cleaners, etchants, and plating solutions themselves. A key is to ask how solutions are prepared and maintained. (If they describe their process as a number of glugs, jugs, scoops, handfuls etc.) Take note, process chemistries should be carefully maintained. If they are proactive they will talk about extending the life of their baths and rinses. Be alert to fixed dump or batch replacement schedules. (like we dump that bath every Thursday) solution life is variable based on use, soil loading.

Rack Plating

Workpieces hung or mounted to frames (racks)Most common and versatile processing methodDragout rates and rinse water use easier to control

Dragout most easily managed due to ability to drain or rinse properly, covered in more detail in the drag-out control areas

Barrel Plating

Parts processed in containment barrelTypically small parts with low level of plating or processing tolerance requirementsDragout rates and water use relatively high

Consequently, poor drainage and difficulty in rinsing make barrel plating a challenge.

Manual Plating

Process steps performed by handSmaller size parts, lower production

Basically un-automated rack plating. Keys are agitation, withdrawal rate, hang time and tilting. Manual process changes must be addressed as a training/management issue. (Worker controlled) Can be potentially very effective if implemented properly.

Automated Plating

Fully Automatedonly requires manual racking and unrackinghigh production quantities and ratesSemi automatedrequires manual control of hoists and railslarger parts, lower production rates, and varied parts

Automated or Semi-automated plating could be either racks or barrels. Main features of automated plating both good or bad is consistent withdrawal rates, rinsing, agitation etc. Semi-automated with hoists has the same procedural constraints as manual plating (worker controlled) training issue.

Keys to Identifying P2 Opportunities at Metal Finishing Facilities

Basics of Metal Finishingdoes the facility monitor and measure their plating or coating solutions, how are additions madedoes the facility have specifications for each part they finish, mil thickness, quality standards?does the facility have procedures and training in place for coating time, withdrawal rate, drain time, rinsing, part orientation?does the facility know addition and flow rates for water in their cleaning and plating solutions and rinses?

Measuring and Understanding Dragout

Now that you have seen an introduction to dragout, we can discuss how to measure and understand it better. If you can measure dragout, you can identify material losses and wastes, and establish a baseline data point so you can measure improvement

Dragout Impacts

Increased plating chemical useIncreased rinse water use or decreased rinse qualityIncreased dragin into next bathIncreased wastewater generation

1.psd

Now lets look at the metal finishing diagram shown earlier during the Metal Finishing the Basics portion of our training.

Dragout from the process or plating bath has multiple impacts.

As shown in the video, dragout causes material losses. The material in this case is the process/plating chemicals. Plating chemical additions are more frequent because of these losses.

The dragout decreases rinse water quality which leads to an increase rinse water flow and use

The excess chemicals from dragout and increase rinse water flow send more rinse water to wastewater treatment

Dragout Impacts (continued)

Increased WWTS treatment chemicalsIncreased WWTS filter cakeIncreased WWTS effluent metal concentration

Increase wastewater generation has a direct correlation to wastewater treatment chemical use. This use increases because more gallons must be treated and there is a higher metal ion concentration from the dragout plating bath.

More chemicals and plating solution in the effluent produces more wastewater sludge and more disposal responsibilities including cost, paperwork, and liability.

Dragout Measurement

Direct volume measurement (dragout volume drained from parts)Metal concentration/conductivity in rinse tanksWastewater contaminant concentration

Once a metal finishers is aware of dragout, they should measure it to establish baseline data and can measure improvements and reductions.

There are 3 methods of measurement;

Direct volume measurement (dragout volume from parts)

Metal concentration/conductivity in rinse tanks

WW contaminant concentration

Conductivity measurement is the easiest and most effective. Direct volume is time consuming and difficult to measure total volume and Wastewater concentration can be expensive because of lab testing. Also, with WW concentration, targeting a particular plating line or solution is difficult.

Calculating Dragout

Vd = (DC)(Vr)/Cp

where:

Vd =dragout volume (L/rack)

DC =increase in rinse water metal concentration per rack or barrel(mg/L/rack)

Vr =rinse tank volume (L)

Cp =process bath metal concentration (mg/L)

Calculating dragout volume in L/rack is possible. The estimated slope of the stagnant rinse tank is 1.5 mg/L/rack. That is delta C. We can assume that the rinse tank volume in 1000 L and the process bath metal concentration is around 70,000 mg/L. Dragout volume is about 21 mL/rack.

Conc = [0.0021 x (conductivity)] + 0.423

0

1

2

3

4

5

6

7

0

500

1,000

1,500

2,000

2,500

3,000

Conductivity (

m

S)

Zn Concentration (ppm)

Good News: conductivity versus concentration is linear.

More Good News: conductivity is easy to measure!

Measuring dragout with conductivity works because conductivity versus concentration is linear. This make measurement easy yet effective.

Using Dragout Measurements

Estimate costs of dragout for particular partsMake cost/benefit decisionsLower dragout vs. slower withdrawal rates Lower dragout vs. longer hang timeWorker trainingIncentive programsWWTS Recovery technologiesBenchmarking

By measuring with conductivity, dragout costs can be estimated for particular parts. This can help when anylyzing what changes are most cost effective and/or save the most money.

Its may help a company make cost/benefit decisions;

Which will have the largest and most effective impact?

Lower Dragout or slower withdrawal rates

Lower dragout or longer hang time

Working training?

Incentive programs?

WWTS?

Recovery technologies to reclaim plating bath

Benchmarking is an important part of dragout measurement. A standard of measurement must to set to establish a reference point for future reductions and improvements.

Dragout Reduction Techniques

Identifying and measuring dragout is the first step. From here, dragout reduction techniques can be applied.

You have a copy of this diagram in your manual.

It is important to look at the 4 ms that cause raw material loss through dragout

Methods, Man, Materials, and Machine

Dragout Reduction:Parts Racking and Handling

Rack maintenancePart geometryPart overlap and angleBarrel rotation and hang time

35

How parts are placed and positioned on a rack effects dragout rates.

Racks are made of metal and be receive the plating solution themselves as shown in the video. This leads to odd shape clusters that increase surface area for dragout to collect. Maintaining the racks are significant

The parts geometry themselves can attribute to dragout. Certain shaped parts like the ones on this slide and collect excess plating solution. They must be racked accordingly, for instance, with a different angle. Also, part overlap is critical so that the plating solution doesnt drip directly onto the next part below.

Finally, barrel rotation and hang time are important factors also. As seen in the video, a few extra seconds on hang time can reduce dragout significantly.

Impact of Barrel Rotation

Barrel rotation also has impacts on dragout. 8 ppm/rack difference or nearly 20% reductions will be significant over a months and years production time.

Dragout Volume vs. Drain Time

Chart1

4.71.61.30.7

5555

2.210.60.4

1.80.80.40.3

20202020

25252525

1.20.60.20.1

35353535

40404040

1450.145

50505050

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Barrel 1, Part 1

Barrel 1, Part 2

Barrel 2, Part 1

Barrel 2, Part 2

Drain Time (seconds)

Dragout (mL)

Sheet1

Dragout (milliliters)

Drip Time (seconds)Barrel 1, Part 1Barrel 1, Part 2Barrel 2, Part 1Barrel 2, Part 2

04.71.61.30.7

5

102.210.60.4

151.80.80.40.3

20

25

301.20.60.20.1

35

40

4510.1

50

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Title

Best Practices for

Metal Finishing

Line Operators

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InfoInput

Facility Name:ABC Metal FinishingDate:05/08/01

UNIT COSTS

1)Type of process solution:Nickel

Unit cost of process solution:$ 7.47/gallon

2)Unit cost of water:$ 3.49/1,000 gallons

(Includes purchase price and

sewer fee)

3)Unit cost of wastewater treatment:$ 51.37/1,000 gallons

(Includes treatment chemicals, maintenance,

permitting, and sludge disposal)

PROCESS INFORMATION

1)Concentration in Process Bath84000.0mg/L

2)Volume of Rinse Tank473.1Liters

(formula includes a conversion from gallons to liters)

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Cal Numbers

DilutionConductivity (microS/cm)Concentration (mg/L)

5001601.00200.00Line Equation

7501420.00100.00slope0.4855794599

10001310.0053.00y-intercept-581.9710495594

20001190.000.00

3000

4000

Blank

City water used for calibration curve

Concentration of metal in plating solution =84,000mg/L

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Cal Graph

200.00

100.00

53.00

0.00

Concentration (mg/L)

Conductivity [microSiemens]

Metal Concentration [mg/L]

Calibration Curve

Ex.1-Racking

FIRST RINSESECOND RINSE

Parts Racked HorizontallyParts Racked VerticallyHorizontalVertical

No. of RacksMetal Concentration (mg/L)Metal Concentration (mg/L)Metal Concentration (mg/L)Metal Concentration (mg/L)

01445.0119.70.001343.070.20.00Start122.011.7124.011.9

11478.0135.733.01365.080.822.0Finish128.012.3128.012.3

21490.0141.545.01376.086.233.0Increase6.000.604.000.40

31512.0152.267.01395.095.452.0

41535.0163.490.01410.0102.767.0Rinse Improvement =0.20mg/L

51560.0175.5115.01430.0112.487.0% Improvement =33%

10.7mg/L/rack8.2mg/L/rack

Process Solution Dragout Calculations

HorizontalVertical


473.1L473.1L

84,000mg/L84,000mg/L

0.060L/rack0.046L/rack

0.016gal/rack0.012gal/rack

WORKSHEET CALCULATIONS

1) Dragout Losses

Parts Racked Horizontally

0.016gal/rack

=55.8gal/month

Parts Racked Vertically

0.012gal/rack

=42.8gal/month

Reduction

Dragout Reduction =13.0gal/month

Percent Reduction =23%

2) Rinse Quality Improvement (second rinse)


Initial =11.67mg/L

Final =12.27mg/L

Increase =0.60mg/L


Initial =11.87mg/L

Final =12.27mg/L

Increase =0.40mg/L

Improvement in Rinse Quality

Improvement =0.20mg/L

3) Rinse Water Use Reduction

% Reduction in Dragout

% Dragout Reduction =23%


Flow rate in 2nd rinse =4.0gpm

=42,240gal/month



=32,395gal/month

Rinse Water Reduction

Reduction =9,845gal/month(based on % drag out reduction)

4) Process Solution Cost Savings:Nickel


Dragout =56gal/month

Cost =$417/month



Cost =$320/month

Cost Savings

Savings =$97/month

5) Rinse Water Use Cost Savings


Water Use =42,240gal/month

Cost =$147/month



Cost =$113/month

Cost Savings

Savings =$34/month(based on % drag out reduction)

6) WWTS Cost Savings



Cost =$2,170/month



Cost =$1,664/month

Cost Savings


7) Summary Table

Parts Racking Position

HorizontalVerticalDifference

Dragout Volume

for 5 racks (gal/rack)0.0160.012

per month (gal/month)55.842.823%

0.60.433%

Rinse Water Use (gal/month)42,24032,39523%

Chemical Costs ($/month)$417$320$97

Water Costs ($/month)$147$113$34

WWTS Costs ($/month)$2,170$1,664$506

Total Savings ($/month) =$637

(These are graph reference numbers below; do not alter!!)

HorizontalVertical

Chemical Costs$417$320

Water Costs$147$113

WWTS Costs$2,170$1,664

Graph1a

0.000.00

33.0022.00

45.0033.00

67.0052.00

90.0067.00

115.0087.00

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HorizontalVertical

Conductivity Increase (mS/cm)


Racks

Conductivity (mS/cm)

Parts Racking

Graph1b

416.60319.50

147.42113.06

2169.871664.13

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Horizontal

Vertical

Cost per Month

Parts Racking

Ex.2-Drain Time


0-Second Drain Time3-Second Drain TimeNo Drain Time5-Second Drain Time


01445.0119.70.001560.0175.50.00Start123.011.8122.011.7

11467.0130.422.01570.0180.410.0Finish126.012.1123.011.8

21490.0141.545.01581.0185.721.0Increase3.000.301.000.10

31512.0152.267.01605.0197.445.0


51560.0175.5126.01650.0219.287.0% Improvement =67%



No Drain Time5-Second Drain Time


473.1L473.1L

84,000mg/L84,000mg/L




1) Dragout Losses


0.017gal/rack

=58.2gal/month


0.013gal/rack

=46.0gal/month

Reduction





Initial =11.77mg/L

Final =12.07mg/L

Increase =0.30mg/L


Initial =11.67mg/L

Final =11.77mg/L

Increase =0.10mg/L








=42,240gal/month



=33,381gal/month






Cost =$434/month



Cost =$343/month

Cost Savings

Savings =$91/month




Cost =$147/month



Cost =$116/month

Cost Savings





Cost =$2,170/month



Cost =$1,715/month

Cost Savings


7) Summary Table

Drain Time

None5-SecondDifference

Dragout Volume



0.30.167%




WWTS Costs ($/month)$2,170$1,715$455





Water Costs$147$116


Graph2a

0.000.00

22.0010.00

45.0021.00

67.0045.00

90.0063.00

126.0087.00

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Racks


Drain Time

Graph2b

434.50343.37

147.42116.50

2169.871714.77

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No Drain Time

5-Second Drain Time

Cost per Month

Drain Time

Ex.3-Spray Rinse


No Spray RinsingSpray RinsingNo Spray RinsingSpray Rinsing


01382.089.10.001318.058.00.00Start134.012.9134.012.9

11404.099.822.01333.065.315.0Finish140.013.5136.013.1

21419.0107.137.01352.074.534.0Increase6.000.602.000.20

31434.0114.352.01356.076.538.0


51468.0130.986.01382.089.164.0% Improvement =67%



No Spray RinsingSpray Rinsing


473.1L473.1L

84,000mg/L84,000mg/L




1) Dragout Losses


0.012gal/rack

=42.8gal/month


0.009gal/rack

=31.2gal/month

Reduction





Initial =12.87mg/L

Final =13.47mg/L

Increase =0.60mg/L


Initial =12.87mg/L

Final =13.07mg/L

Increase =0.20mg/L








=42,240gal/month



=30,766gal/month






Cost =$320/month



Cost =$233/month

Cost Savings

Savings =$87/month




Cost =$147/month



Cost =$107/month

Cost Savings





Cost =$2,170/month



Cost =$1,580/month

Cost Savings


7) Summary Table

Spray Rinsing

NoneSpray RinsingDifference

Dragout Volume



0.60.267%




WWTS Costs ($/month)$2,170$1,580$589





Water Costs$147$107


Graph3a

0.000.00

22.0015.00

37.0034.00

52.0038.00

70.0050.00

86.0064.00

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Racks


Spray Rinsing

Graph3b

319.50232.71

147.42107.37

2169.871580.43

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No Spray Rinsing

Spray Rinsing

Cost per Month

Spray Rinsing

Ex.4-T&D


No Tilting and DrainingTilting and DrainingNo Tilting and DrainingTilting and Draining


01532.0161.90.001478.0135.70.00Start120.011.5120.011.5

11551.0171.219.01486.0139.68.0Finish125.012.0121.011.6

21567.0178.935.01497.0144.919.0Increase5.000.501.000.10

31586.0188.254.01509.0150.831.0


51626.0207.694.01532.0161.954.0% Improvement =80%



No Tilting and DrainingTilting and Draining


473.1L473.1L

84,000mg/L84,000mg/L




1) Dragout Losses


0.013gal/rack

=46.6gal/month


0.008gal/rack

=27.9gal/month

Reduction





Initial =11.47mg/L

Final =11.97mg/L

Increase =0.50mg/L


Initial =11.47mg/L

Final =11.57mg/L

Increase =0.10mg/L








=42,240gal/month



=25,265gal/month






Cost =$348/month



Cost =$208/month

Cost Savings

Savings =$140/month




Cost =$147/month



Cost =$88/month

Cost Savings





Cost =$2,170/month



Cost =$1,298/month

Cost Savings


7) Summary Table

Tilting and Draining

NoneTilt and DrainDifference

Dragout Volume



0.50.180%




WWTS Costs ($/month)$2,170$1,298$872

Total Savings ($/month) =$1,071




Water Costs$147$88


Graph4a

0.000.00

19.008.00

35.0019.00

54.0031.00

70.0042.00

94.0054.00

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Racks



Graph4b

348.25208.30

147.4288.18

2169.871297.87

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No Tilting and Draining


Cost per Month


Summary Table

Demonstration Summary

Chemical Use SavingsWater Use SavingsWWTS SavingsTOTAL

Parts Racking$97$34$506$637

Drain Time$91$31$455$577

Spray Rinsing$87$40$589$716

Tilt and Drain$140$59$872$1,071

These are important referenced graphs below!! Do not modify!!!

Dragout

Original TechniqueModified Technique

Parts Racking55.842.8

Drain Time58.246.0

Spray Rinsing42.831.2

Tilt and Drain46.627.9

% Improvement

Tilt and Drain40%

Spray Rinsing27%

Drain Time21%

Parts Racking23%

Cost

97.1034.36505.74

91.1330.92455.10

86.7940.05589.44

139.9559.24872.00

Chemical Use Savings

Water Use Savings

WWTS Savings

Cost Savings

Cost Summary

Dragout

55.7742.77

58.1745.97

42.7731.15

46.6227.88

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Original Technique

Modified Technique

Dragout (gal/month)

Dragout Summary

% Reduction

0.40

0.27

0.21

0.23

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Percent Improvement

Dragout Reduction

36

Drain time should be increased but only with reasonable time standards. As mentioned earlier, conductivity can be used to decide between dragout reduction methods and how they are implemented. Based on this graph, drain times greatest impact on dragout is the 5 to 10 seconds

Dragout Reduction: Worker Practices

Withdrawal rateDrainage timeTiltingUse hang bars and other devices

36

Many metal finishing shops have manual operations or semi-manual operations. Worker practices are therefore important when completing a dragout reduction initiative.

Withdrawal rates, drainage time, tilting and hang bars can influence losses of plating solutions.

Impacts of Withdrawal Rate

The video demonstrated how the speed of withdrawal rates impact dragout rates. A faster withdrawal rate leaves a thicker film on part than a slow rate.

Dragout Reduction:Process Layout, Maintenance

Tank spacing and drain boardsTank sequenceDragout tanks (with or without sprays)Spray rinses

36

Process layout and maintenance can also influence dragout reduction. The video discussed proper tank spacing and drain boards.

The right tank sequence in important also, like including dragout tanks and spray rinsing.

Dragout Tanks

Single stage rinseRinse water flow rate = 2 gpmDragout rate = 0.25 gphCadmium discharge = 0.23 lb/day

Dragout tank followed by rinse tankRinse water flow rate = 0.6 gpmDragout rate = 0.20 gphCadmium discharge = 0.07 lb/day

Installing dragout tank that collect excess plating bath and returns to original bath reduces metal discharge by 30% per day. At the same time, rinse water flow rate was reduced by 30% also which yields water savings

Sprays: More than a Rinse!

Parts moved directly to rinse tank from plating bathDragout rate = 0.25 gphRinse water flow rate = 2 gpmChromium discharge = 2.2 lb/day

Parts rinsed with mist spray above plating tankDragout rate = 0.13 gphRinse water flow rate = 1 gpmChromium discharge = 1.1 lb/day

Spray rinsing, which we will go into more detail this afternoon can reduce metal discharge by more than 50% and reduce rinse water flow without installing a dragout tank. Sometimes both dragout tanks and spray rinse can be used it plating operations has space.

Dragout Reduction with Spray Rinse

Cost savings of a typical spray rinse system is 60%.

Conductivity Control Systems

This section focuses on how to utilize the relationship between conductivity and dragout to optimize rinse water usage. From discussion earlier conductivity and dragout are directly related and can be used to effectively measure dragout (increasing concentration of ions) in the subsequent rinse baths.


Conductivity Controldoes the facility use conductivity measurement to manage their rinse system(s)?if they have a system, what type is it, how do they operate it, what are their results?if they do not have system do they know the relative costs and benefits of installing one?

Analyzer

The system brainReceives input from sensorDisplays conductivity readingDigital, analog, or noneSends output signal to solenoid valveKey features:Programmable set point Programmable deadband

These components are an example of a fully automated conductivity control system. There could be wide range of layouts and degree of automation utilized in implementing this approach. Including manually adjusting flows utilizing a continuous readout conductivity meter or even a hand held unit and control charting.

Conventional Sensor

The sensor has an anode and cathode which is placed in a solutionElectrical potential is measured between these electrodesProne to fouling$150-250

Problems with this system are caused because the cathode in the solution is going to plate with the metal ions in the solution. This requires constant cleaning & recalibration of the sensor.

Electrodeless Sensor

Uses two parallel torroidsNon-conductive casing (polypropylene or PVDF)No electrodes; no foulingCan measure full range of conductivity$435-635

Measures an induced current in the solution. This method avoids the fouling problems with conventional sensors.

Sensor Installation

Sensor placementHalfway down from top of water levelAway from stagnant areasAway from clean water inletIn final stage of multistage counterflow rinseGood circulation of rinse waterMechanical mixingDouble dipping parts

Keys to good control are representative measurement of the conductivity in the tank. Another item not on the list would be to have the sensor stationary and not in various positions over time. Good circulation of rinse water also is very helpful and can be achieved through mechanical mixing or double dipping of parts in the rinse tank.

Determining the Initial Set Point

Establishing the initial set point is very important for assuring that changing the rinse flows will not effect product quality. Product quality and conductivity need to measured carefully and measured together. The concept is the same as many other P2 opportunities, utilize the least amount of a raw material while maintaining product quality. The net result will be an increase in efficiency and a consistency in the product quality due to process control.

Rinse Water Use

40,000

80,000

120,000

160,000

5/6

5/28

6/17

7/15

8/5

8/26

9/16

10/7

10/28

11/18

Week

Weekly Rinse Water Use (gal.)

Installation

Note: No change in production occurred during the evaluation period.

This is the effect seen by establishing a set point and operational range for tank refill, and operating the rinse tanks with the controls in place. As you can see the effect is very dramatic and is typical for instituting controls.

Spray Rinse Systems and Design

As mentioned in the Drag-out portion of this mornings session, spring rinsing can reduce dragout significantly.

But spray rinsing has other benefits;

Less raw material wasted because of reduced dragout

Less contamination of process baths by dragin (Ill show an example of this process later)

Lower rinse water flow rates required in running rinses

More efficient, higher quality rinsing

Benefits of Reducing Rinse Water

Lower water bills and sewer feesWastewater treatment impactsLower treatment chemical costsHigher retention timeLess O&M requirementsDecreased sludge generation

Similar to dragout reduction, reducing rinse water can have to same WWTP benefits.

A efficient rinse water system can lower water bills and sewer fees.

Less water means lower treatment chemical costs and a higher retention time due to a lower flow rate.

In turn, Operational and maintenance costs and requirements are reduced

Techniques that Improve Rinse Efficiency

AgitationRack motionForced air and/or forced waterSpraysDouble dippingFlow Controls and Water QualityFlow restrictorsConductivity control systemsTap water vs. deionized water

39

Some basic techniques to improve rinse efficiency

Agitation

-rack motion-manual or automatic

-forced air and/or forced water- careful to use only enough air to blow excess dragout off part. To much can lead to flashing or oxidation of part. Usually air and water mix is better. Ill provide example later in this session

-sprays

-double dipping

Flow controls & water quality

-flow restrictors-must be used properly to determine most efficient flow

-conductivity control systems-Ron covered this

-tap water vs. deionized water-depends on product/customer specs and production process

Techniques that Improve Rinse Efficiency

Tank DesignSize (not bigger than necessary)Eliminate short-circuitingTank LayoutMultiple tanksCountercurrent rinses are extremely efficient 90% reduction compared to a single rinseMost old shops can not accommodate the larger footprint

40

Techniques continued

Tank Design

-size is important (a large tank does not mean better rinse efficiency)

-eliminating short-circuiting-improper mixing of rinse tank/stratification

Tank Layout

-multiple tanks-dragout tanks and rinse tanks

-Countercurrent or counterflow rinsing can often yield 90% reduction in rinse water compared to single rinse

-however, many old shops cannot accommodate major layout changes or the large tank footprint

Counter Current Rinse System

41

As I mentioned, counter current or counter flow is another rinse water reduction technique.

Here is an general diagram describing the process. The cleanest rinse and rinse water inlet is always in the last rinse tank. It then flows over or is pumped back to the first rinse tank.

Counterflow also Reduces Dragin

Single-stage zincate rinse Rinse water flow rate = 2 gpmDragin rate into bath = 0.50 gphZn buildup in EN bath = 6 ppm/day

Two-stage counterflow zincate rinse Rinse water flow rate = 1 gpmDragin rate into bath = 0.40 gphZn buildup in EN bath = 0.02 ppm/day

Example of counterflow rinsing reducing dragin

A zincate rinse before an electroless nickel bath. Before counterflow rinse,

Rinse water flwo rate was 2 gpm

Original zinc conc. In rinse was 415ppm

After two-stage counterflow zincate rinse,

Final rinse stage zinc conc.is 222ppm

Electroless bath dragin was 6.1 ppm of Zinc per day and now is 0.02 ppm

Thats is a 305% reduction!!!

Reactive Rinsing

47

Reactive Rinsing Example
172 Acid Bath Dumps/Year200 gallon bath$23k/year for bath makeupIn-Shop Measurements:Alkaline Rinse pH:12.15Acid Rinse pH:1.32Combination:1.77Estimated 50% Reduction in Acid Use/DumpsCapital: $1,250Payback:

Spray Rinse Systems and Design

Spray rinsing might work well and save money and plating bath, but it must be set-up and properly design to accomplish any of these reductions


Rinse Tank Optimization & Spray Rinsingare any measures in place to extend the life of the rinse baths, skimmers, agitation, sludge removal, water treatment?are spray rinses utilized, if so, where are they located, how are they operated and why?are rinse tanks utilizing counter current flow, are there flow restrictors or controls?is the quality of the rinse water monitored or measured?has the facility experimented with different rinse configurations, flows, or sprays?

Sprays Reduce Dragout by 58%

20.8 gallons of

dragout/month

50.0 gallons of

dragout/month

Number of Racks

Conductivity (S/cm)

58% Reduction

250

200

150

100

50

0

0 10 20 30 40 50 60

Spray Rinses Off

Spray Rinses On

Spray rinsing on Nickel line reduced dragout by 58%

50.0 gallons per month to 20.8 gallons

Air-Atomized Spray Guns

As mentioned in the beginning of this session, the correct spray rinse system and equipment is important. Using a garden hose spray gun compared to air-atomized spray gun can use over 36,000 gallon/yr more.

Air-Atomized Spray Guns

AIR-ATOMIZING SPRAY RINSING RESULTS

AnnualAnnual

ReductionSavings

Spray Rinse Water Use36,960 gal.$464

Wastewater Generation36,960 gal.$715*

Total Savings = $1,179/year

Total Cost = $636

Payback Period < 7 months

*Annual savings for wastewater generation is based on estimated treatment chemical use reduction.

These savings are significant with a short payback period

Sprays Over Heated Baths

_992259471.xls

Sheet: Chart4

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12.0

14.0

14.0

16.0

16.0

0.0

0.0

11.0

4.0

5.0

4.0

8.0

4.0

12.0

10.0

21.0

10.0

23.0

11.0

26.0

9.0

32.0

0.0

0.0

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2.0

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4.0

6.0

6.0

8.0

8.0

10.0

10.0

12.0

12.0

14.0

14.0

16.0

16.0

0.0

0.0

4.0

11.0

4.0

5.0

4.0

8.0

10.0

12.0

10.0

21.0

11.0

23.0

9.0

26.0

32.0

0.0

0.0

2.0

2.0

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4.0

6.0

6.0

8.0

8.0

10.0

10.0

12.0

12.0

14.0

14.0

16.0

16.0

0.0

0.0

11.0

4.0

5.0

4.0

8.0

4.0

12.0

10.0

21.0

10.0

23.0

11.0

26.0

9.0

32.0

SPRAY GUN

WATER USE (gallons per day)

High-flow spray nozzle

297.0

Air-atomizing spray gun

176.0

0.0

0.0

You can see a 61% reduction in the conductivity slope and how bath life can be extended.

Sprays Over Heated Baths

FOG SPRAY RINSING RESULTS

AnnualAnnual

ReductionSavings

Black Dye Use43.2 lb$2,419

Wastewater Generation14,856 gal.$1,247*

Total Savings = $3,666

Total Cost = $355


* Annual savings for wastewater generation includes $186 in process water purchases and $1,061 in wastewater treatment O&M.

Great payback of less than 2 months

Tools and Resources for Assistance

Available Tools

Metal Finishing P2 Videos1. DHWM Preserving the Legacy Series: The Metal Plating and Finishing Industries2. USEPA Pollution Prevention for Metal Platers: Drag-out ReductionAdvanced P2 Technical Assistance

- TECHSOLVE P2IRIS Metal Finishing http://www.techsolve.org/iamsorg/p2iris/metalfinish/default.html

U.S. EPA/NAMF/AESF

- Strategic Goals Program http://www.strategicgoals.org/

Good morning, welcome to the Metal Finishing Sector Pollution Prevention Workshop

Value of this training. This training should make you more comfortable in identifying potential pollution prevention opportunities at metal finishers and coaters that you inspect. We hope to give a broad but accurate overview of plating processes and situations that you may encounter. Each section will have some basic keys to look for when visiting a plating facility. We want you to be confident in suggesting options for facilities to pursue and know where to find resources and assistance should a facility be open to considering P2 opportunities.

9

This is a very basic input output diagram to begin to consider opportunities for reductions in raw materials and subsequent waste streams.

Basic metal finishing process usually incorporate these 3 major steps

Some type of cleaning and preparation step, in order to allow the work piece to accept a coating. The coating or Plating process where metal ions are attached to the surface by a bond Some sort of protective coating to seal the finish

Surface preparation will usually start with removal of fluids from machining and or shipping protective coatings. This step should be the beginning of the P2 focus at a facility. Carry over from the cleaning or preparation phase will impact the plating solution and possibly subsequent rinses.

Alkaline cleaning: oil, dirt, coating removal

Electropolishing: reverse plating process, remove thin coating of metal from part, shiny surface (from which the name is taken)

Oxide removal: acid stripping of rust also done for surface preparation, longer is pickling.

Electroplating is the electronic deposition of a metal ion on the surface of a negatively charged work piece.

Electroless plating is the same deposition process except current is not used, a solution of metal ions still deposits on the work piece.

Anodizing: this process is basically the same as electropolishing except the purpose is to form a thin oxide on the surface of the part.

Chromate Conversion Coating: this process uses chromic acid to form a thin gel like film of chromic oxide and aluminum oxide on the part surface. This is frequently used so that paint or adhesives will adhere to aluminum parts.

Phosphating: a thin layer of phosphate crystals on the metal surface, for coating adhesion.

Slide 17

Plating Line/Department Except for vapor degreasing, which normally is performed off-line, plating operations are normally incorporated into a sequence of tanks, called a "line."

A plating line may be designed to produce a single coating or a number of coatings. While not always the case, the process line contains tanks lined up in sequential order. Automated lines may or may not contain tanks in sequential order.

A zinc plating line may therefore consist of 13 tanks, each containing a chemical processing solution or rinse water, soak clean, electroclean, rinse, acid, rinse, zinc plate, rinse, bright dip, rinse, chromate, rinse, hot water rinse, and dry. If the line is for barrel plating, each tank may have one or more "stations," that is, places to put a barrel. A six-station zinc plating tank can plate six barrel-loads of parts at one time. To economize, some shops may have one cleaning line that services several plating lines. There also are tanks for rack stripping, stripping rejects, purifying contaminated solutions or holding solutions that are only sporadically used. The entire lineup of tanks and lines creates a "layout" of the shop, with parts entering the plating department from one direction, traveling through the process lines, and leaving the plating department.

Rinse water effluent receives metals loading, cleaners, etchants and often requires pH adjustment. Volume of the waste water is a key, along with any alternative chemistries for cleaning, coating, etc. Always ask if a process step is required by the customer, or if alternatives would be acceptable.

28

Least toxic chemicals, starting with coolants fluids or lubes if parts are machined, then cleaners, etchants, and plating solutions themselves. A key is to ask how solutions are prepared and maintained. (If they describe their process as a number of glugs, jugs, scoops, handfuls etc.) Take note, process chemistries should be carefully maintained. If they are proactive they will talk about extending the life of their baths and rinses. Be alert to fixed dump or batch replacement schedules. (like we dump that bath every Thursday) solution life is variable based on use, soil loading.

Dragout most easily managed due to ability to drain or rinse properly, covered in more detail in the drag-out control areas

Consequently, poor drainage and difficulty in rinsing make barrel plating a challenge.

Basically un-automated rack plating. Keys are agitation, withdrawal rate, hang time and tilting. Manual process changes must be addressed as a training/management issue. (Worker controlled) Can be potentially very effective if implemented properly.

Automated or Semi-automated plating could be either racks or barrels. Main features of automated plating both good or bad is consistent withdrawal rates, rinsing, agitation etc. Semi-automated with hoists has the same procedural constraints as manual plating (worker controlled) training issue.

Now that you have seen an introduction to dragout, we can discuss how to measure and understand it better. If you can measure dragout, you can identify material losses and wastes, and establish a baseline data point so you can measure improvement

Now lets look at the metal finishing diagram shown earlier during the Metal Finishing the Basics portion of our training.

Dragout from the process or plating bath has multiple impacts.

As shown in the video, dragout causes material losses. The material in this case is the process/plating chemicals. Plating chemical additions are more frequent because of these losses.

The dragout decreases rinse water quality which leads to an increase rinse water flow and use

The excess chemicals from dragout and increase rinse water flow send more rinse water to wastewater treatment

Increase wastewater generation has a direct correlation to wastewater treatment chemical use. This use increases because more gallons must be treated and there is a higher metal ion concentration from the dragout plating bath.

More chemicals and plating solution in the effluent produces more wastewater sludge and more disposal responsibilities including cost, paperwork, and liability.

Once a metal finishers is aware of dragout, they should measure it to establish baseline data and can measure improvements and reductions.

There are 3 methods of measurement;

Direct volume measurement (dragout volume from parts)

Metal concentration/conductivity in rinse tanks

WW contaminant concentration

Conductivity measurement is the easiest and most effective. Direct volume is time consuming and difficult to measure total volume and Wastewater concentration can be expensive because of lab testing. Also, with WW concentration, targeting a particular plating line or solution is difficult.

Calculating dragout volume in L/rack is possible. The estimated slope of the stagnant rinse tank is 1.5 mg/L/rack. That is delta C. We can assume that the rinse tank volume in 1000 L and the process bath metal concentration is around 70,000 mg/L. Dragout volume is about 21 mL/rack.

Measuring dragout with conductivity works because conductivity versus concentration is linear. This make measurement easy yet effective.

By measuring with conductivity, dragout costs can be estimated for particular parts. This can help when anylyzing what changes are most cost effective and/or save the most money.

Its may help a company make cost/benefit decisions;

Which will have the largest and most effective impact?

Lower Dragout or slower withdrawal rates

Lower dragout or longer hang time

Working training?

Incentive programs?

WWTS?

Recovery technologies to reclaim plating bath

Benchmarking is an important part of dragout measurement. A standard of measurement must to set to establish a reference point for future reductions and improvements.

Identifying and measuring dragout is the first step. From here, dragout reduction techniques can be applied.

You have a copy of this diagram in your manual.

It is important to look at the 4 ms that cause raw material loss through dragout

Methods, Man, Materials, and Machine

35

How parts are placed and positioned on a rack effects dragout rates.

Racks are made of metal and be receive the plating solution themselves as shown in the video. This leads to odd shape clusters that increase surface area for dragout to collect. Maintaining the racks are significant

The parts geometry themselves can attribute to dragout. Certain shaped parts like the ones on this slide and collect excess plating solution. They must be racked accordingly, for instance, with a different angle. Also, part overlap is critical so that the plating solution doesnt drip directly onto the next part below.

Finally, barrel rotation and hang time are important factors also. As seen in the video, a few extra seconds on hang time can reduce dragout significantly.

Barrel rotation also has impacts on dragout. 8 ppm/rack difference or nearly 20% reductions will be significant over a months and years production time.

36

Drain time should be increased but only with reasonable time standards. As mentioned earlier, conductivity can be used to decide between dragout reduction methods and how they are implemented. Based on this graph, drain times greatest impact on dragout is the 5 to 10 seconds

36

Many metal finishing shops have manual operations or semi-manual operations. Worker practices are therefore important when completing a dragout reduction initiative.

Withdrawal rates, drainage time, tilting and hang bars can influence losses of plating solutions.

The video demonstrated how the speed of withdrawal rates impact dragout rates. A faster withdrawal rate leaves a thicker film on part than a slow rate.

36

Process layout and maintenance can also influence dragout reduction. The video discussed proper tank spacing and drain boards.

The right tank sequence in important also, like including dragout tanks and spray rinsing.

Installing dragout tank that collect excess plating bath and returns to original bath reduces metal discharge by 30% per day. At the same time, rinse water flow rate was reduced by 30% also which yields water savings

Spray rinsing, which we will go into more detail this afternoon can reduce metal discharge by more than 50% and reduce rinse water flow without installing a dragout tank. Sometimes both dragout tanks and spray rinse can be used it plating operations has space.

Cost savings of a typical spray rinse system is 60%.

This section focuses on how to utilize the relationship between conductivity and dragout to optimize rinse water usage. From discussion earlier conductivity and dragout are directly related and can be used to effectively measure dragout (increasing concentration of ions) in the subsequent rinse baths.

These components are an example of a fully automated conductivity control system. There could be wide range of layouts and degree of automation utilized in implementing this approach. Including manually adjusting flows utilizing a continuous readout conductivity meter or even a hand held unit and control charting.

Problems with this system are caused because the cathode in the solution is going to plate with the metal ions in the solution. This requires constant cleaning & recalibration of the sensor.

Measures an induced current in the solution. This method avoids the fouling problems with conventional sensors.

Keys to good control are representative measurement of the conductivity in the tank. Another item not on the list would be to have the sensor stationary and not in various positions over time. Good circulation of rinse water also is very helpful and can be achieved through mechanical mixing or double dipping of parts in the rinse tank.

Establishing the initial set point is very important for assuring that changing the rinse flows will not effect product quality. Product quality and conductivity need to measured carefully and measured together. The concept is the same as many other P2 opportunities, utilize the least amount of a raw material while maintaining product quality. The net result will be an increase in efficiency and a consistency in the product quality due to process control.

This is the effect seen by establishing a set point and operational range for tank refill, and operating the rinse tanks with the controls in place. As you can see the effect is very dramatic and is typical for instituting controls.

As mentioned in the Drag-out portion of this mornings session, spring rinsing can reduce dragout significantly.

But spray rinsing has other benefits;

Less raw material wasted because of reduced dragout

Less contamination of process baths by dragin (Ill show an example of this process later)

Lower rinse water flow rates required in running rinses

More efficient, higher quality rinsing

Similar to dragout reduction, reducing rinse water can have to same WWTP benefits.

A efficient rinse water system can lower water bills and sewer fees.

Less water means lower treatment chemical costs and a higher retention time due to a lower flow rate.

In turn, Operational and maintenance costs and requirements are reduced

39

Some basic techniques to improve rinse efficiency

Agitation

-rack motion-manual or automatic

-forced air and/or forced water- careful to use only enough air to blow excess dragout off part. To much can lead to flashing or oxidation of part. Usually air and water mix is better. Ill provide example later in this session

-sprays

-double dipping

Flow controls & water quality

-flow restrictors-must be used properly to determine most efficient flow

-conductivity control systems-Ron covered this

-tap water vs. deionized water-depends on product/customer specs and production process

40

Techniques continued

Tank Design

-size is important (a large tank does not mean better rinse efficiency)

-eliminating short-circuiting-improper mixing of rinse tank/stratification

Tank Layout

-multiple tanks-dragout tanks and rinse tanks

-Countercurrent or counterflow rinsing can often yield 90% reduction in rinse water compared to single rinse

-however, many old shops cannot accommodate major layout changes or the large tank footprint

41

As I mentioned, counter current or counter flow is another rinse water reduction technique.

Here is an general diagram describing the process. The cleanest rinse and rinse water inlet is always in the last rinse tank. It then flows over or is pumped back to the first rinse tank.

Example of counterflow rinsing reducing dragin

A zincate rinse before an electroless nickel bath. Before counterflow rinse,

Rinse water flwo rate was 2 gpm

Original zinc conc. In rinse was 415ppm

After two-stage counterflow zincate rinse,

Final rinse stage zinc conc.is 222ppm

Electroless bath dragin was 6.1 ppm of Zinc per day and now is 0.02 ppm

Thats is a 305% reduction!!!

47

Spray rinsing might work well and save money and plating bath, but it must be set-up and properly design to accomplish any of these reductions

Spray rinsing on Nickel line reduced dragout by 58%

50.0 gallons per month to 20.8 gallons

As mentioned in the beginning of this session, the correct spray rinse system and equipment is important. Using a garden hose spray gun compared to air-atomized spray gun can use over 36,000 gallon/yr more.

These savings are significant with a short payback period

You can see a 61% reduction in the conductivity slope and how bath life can be extended.

Great payback of less than 2 months

Space

Constraints

Raw Material

Loss Through

Dragout

Parts

Process Baths Too Concentrated

Racking Angle

Established Concentration

Higher Than Necessary

High Evaporation

Rate

Worker Practices

Removal Rate

Too Fast

Over-add Chemicals

Inadequate Worker

Training

Habit

Costs

Space Constraints

Process Line Configuration

No Dragout Tanks

Old Design

Production Rate

Pressures

No Spray Rinses on

Process Tanks

Too Much Maintenance

Lack of Awareness

No Drainage Boards

Lack of

Awareness

Space Between Tanks

Old Layout

Drainage Boards

Not Maintained

Frequent Process

Changes

Rack Design

Parts Overlap

on Rack

Rack Design

Chemical Supplier

Recommendations

Worker Practices

and Assumptions

Temperature Too High

Part Configuration

and Surface Area

Part Design

Supplier Concern

About Dragout

No Statistical

Process Control

Inadequate Worker Training

Production Rate Pressures

Lack of Motivation

Drainage Time Too Short

800

600

400

200

0

1

2

3

4

5

6

7

8

Slope = 41 ppm/rack

Slope = 49 ppm/rack

Number of Barrels

Zinc (ppm)

Rotation Off

Rotation On

Drain Time

None5-SecondDifference

Dragout Volume



Rinse Quality (

m

g/L)0.30.167%




WWTS Costs ($/month)$2,170$1,715$455

Total Savings ($/month) = $577

0

1

2

3

4

5

01020304050

Drain Time (seconds)

Dragout (mL)

Barrel 1, Part 1

Barrel 1, Part 2

Barrel 2, Part 1

Barrel 2, Part 2

Wastewater

0.23 lbs Cd/day

Cadmium Bath

14,000 ppm Cd

Dragout

0.25 gph

Rinse

29 ppm Cd

Before

Rinsewater

2 gpm

Wastewater

0.07 lbs Cd/day

Cadmium Bath

14,000 ppm Cd

Dragout

0.2 gph

Dragout Tank

5,386 ppm Cd

After

Rinsewater

0.6 gpm

Rinse

29 ppm Cd

Wastewater

2.2 lbs chrome/day

Chromium Bath

130,000 ppm Cr

6+

Dragout

0.25 gph

Rinse

270 ppm Cr

6+

Before

Rinsewater

2 gpm

Wastewater

1.1 lbs chrome/day

Chromium Bath

130,000 ppm Cr

6+

Dragout

0.13 gph

Rinse

270 ppm Cr

6+

After

Rinsewater

1 gpm

0

500

1,000

1,500

2,000

2,500

3,000

3,500

4,000

Day 1

Day 2

Day 3

Day 4

Day 5

Day 6

Day 7

Day 8

Day 9

Day 10

Day 11

Day 12

Day 13

Day 14

Day 15

Date

Conductivity (

S)

Initial Set Point

Zincate Rinse

415 ppm Zn

Zn

Dragin

Electroless

Nickel Bath

6.1 ppm Zn

increase per day

Before

To EN

Rinse

Zincate

Dragout

0.5 gph

Zincate

Rinse

666 ppm Zn

Zn

Dragin

Electroless

Nickel Bath

0.02 ppm Zn

increase per day

After

To EN

Rinse

Zincate

Dragout

0.4 gph

Zincate

Rinse

2.22 ppm Zn

Zn

Dragin

Total water

use reduction:

36,960 gal/yr

0

50

100

150

200

250

300

350

Garden hose spray gun Air-atomized spray gun

Water use (gal/day)

AIR-ATOMIZING SPRAY RINSING

RESULTS

Annual

Annual

Reduction

Savings

Spray Rinse Water Use

36,960 gal.

$464

Wastewater Generation

36,960 gal.

$715*

Total Savings = $1,179/year

Total Cost = $636


*Annual savings for wastewater generation is based on estimated

treatment chemical use reduction.

Slope = 1.85 uS/cm/rack

Slope =0.73 uS/cm/rack

0

5

10

15

20

25

30

35

0

5

10

15

20

Number of Racks Processed

Conductivity Increase (uS/cm)

Without Fog Spray

With Fog Spray

FOG SPRAY RINSING RESULTS

Annual

Annual

Reduction

Savings

Black Dye Use

43.2 lb

$2,419

Wastewater Generation

14,856 gal.

$1,247*

Total Savings = $3,666

Total Cost = $355


*

Annual savings for wastewater generation includes $186 in

process water purchases and $1,061 in wastewater treatment O&M.

Documents

[PPT]PowerPoint Presentation - Ohioweb.epa.ohio.gov/opp/Metal Finishing Training Web.ppt · Web viewMetal Finishing (Electroplating) P2 Workshop Part 1 Ohio EPA Division of Hazardous