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OAR Box 1814 

Prepped by Ollie Stewart 

Document Number: 

45) ll-B-23 

Docket Number: 

A-88-02 

Printed 11/7/2008 7:22:08 AM Sheet 45 of 63 
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A-88-02 

MIDWEST RESEARCH INSTITUTI 

4505 Creeamoor Roa. 

Raleigh N C 2761 

Telephone (919) 781-575 

Date: March 16, 1987 

(Revised and updated from May 21, 1985, Trip Report) 

(Finalized April 2, 1987) 

Subject: Site Visit—Delco Products Division, General Motors Corporation 

Chromium Electroplating NESHAP 

EPA Contract 68-02-3817; ESED Project 85/02a 

MRI Project 7717-K 

From: Robin Barkerj\ hfi 

To: Al Vervaert 

ESED/ISB/SSS (MD-13) 

U. S. Environmental Protection Agency 

Research Triangle Park, N.C. 27711 

I. Purpose 

The purpose of this site visit was to determine the suitability of 

the decorative chromium plating operations for uncontrolled chromium 

emissions testing. The background information on the decorative chromium 

plating operations at this plant was gathered 1n a previous visit to the 

plant on March 15, 1985. 

II. Place and Date 

Delco Products Division 

General Motors Corporation 

Livonia Plant 

13000 Eckles Road 

Livonia, Michigan 48151 

(313) 464-5155 

January 21, 1987 

III. Attendees 

Delco Products Division, General Motors Corporation (Delco) 

Harry Cameron, A1r Pollution Control Supervisor 

Larry Siersma, Environmental Control Engineer 

U. S. Environmental Protection Agency (EPA) 

Al Vervaert, ISB 

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Midwest Research Institute (MRI) 

Robin Barker 

IV. Discussion 

The visit began with a discussion about the emission control system 

1n place on the decorative chromium plating lines at the Delco Products 

plant. The discussion was followed by a tour of the plating facility. 

A. General 

The Delco Products plant 1s an original equipment manufacturer of 

bumpers for the automotive Industry. There are five decorative chromium 

plating lines at this plant: Line Nos. 1 through 3 were Installed from 27 

to 32 years ago, and Line Nos. 4 and 5 were Installed 17 years ago. The 

plant operates two shifts per day, 5 days per week. 

B. Process 

Each plating line consists of about 20 tanks that contain various 

plating and cleaning solutions. The lines are serviced by automatically 

controlled conveyors that transfer racks containing up to 14 bumpers to 

each tank 1n sequence. The chromium plating segment of each line consists 

of a plating tank and several rinse tanks. 

Each chromium plating tank measures 6.10 meters (m) (20 feet [ft]) 

1n length, 3.66 m (12 ft) In width, and 2.74 m (9 ft) 1n depth and 1s 

divided Into three cells that are 2.04 m (6.7 ft) 1n length. Each 

3-celled tank holds 64,360 liters (a) (17,000 gallons [gal]) of plating 

solution, which contains chromic add 1n a concentration of 247 to 

374 grams per liter (33 to 50 ounces per gallon) of water. Sulfuric ad d 

1s used as a catalyst 1n a 180:1 (chromic add to sulfuric acid) ratio. 

The solutions have been disposed of once since they were originally made 

up; makeup water and chromic ad d are added continually to replace losses 

due to evaporation and dragout. The total chromic ad d consumption at 

this plant 1s 6,804 kilograms (15,000 pounds) per month. 

Typically, a rack remains 1n one cell of a chromium plating tank for 

a little over 2 minutes to receive a chromium plate thickness of 

0.305 micrometers (0.012 mils). The electrodes 1n each cell are charged 

by two separate transformer/rectifiers. During a typical plating cycle, 

the tank operates at 16 to 17 volts (V) and 8,500 to 10,000 amperes (A). 

The electrical settings are determined by the required current density for 

a particular rack of bumpers. Typical current densities are 1n the range 

of 1,615 to 2,150 amperes per square meter (150 to 200 amperes per square 

foot). 

C. Emission Control 

Plant personnel said that about 99 percent of the gas emitted from a 

chromium plating tank 1s due to the formation of hydrogen gas bubbles at 

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the surface of the Items being plated (cathode). The remaining 1 percent 

1s caused by the formation of oxygen gas at the surface of the lead 

anodes. The plant believes operating current is the predominant factor 

affecting emissions from a typical tank. 

The ventilation system on the tanks appeared to be effectively 

drawing mist into the control system during the visit. Each chromium 

plating tank has two single-sided lateral hoods on the ends of the tank 

and two double-sided lateral hoods between each plating cell that draw 

emissions from along the 3.7 (|2-ft) width (see Figure 1). About 

8503cub1c meters per minute (m /min) (30,000 cubic feet per minute 

[ft /m1n]) of air are drawn from the plating tanks on Line Nos. 1 and 3. 

About 990 m /m1n (35,000 ft /m1n) are drawn from the tanks on Line Nos. 4 

and 5. The Occupational Safety and Health Administration (OSHA) requires 

that ambient chromium levels remain below 0.05 milligrams per cubic meter 

(mg/m ) (2.19x10" grains per cubic foot [gr/ft ]), and monthly monitoring 

has shown the levels at this plant to be under 0.02 mg/m 

(8.74x10 gr/ft ) . 

This plant has had about six different control device configurations 

since 1t began operating. The emission control system 1s unique and 

combines both off-the-shelf and specially designed equipment. Each system 

routes exhaust gases from one chromium plating tank through a packed-bed 

spray tower scrubber, an impingement mist eliminator, a 2-1nch-th1ck 

polypropylene blanket, a fan, a water impingement tank, a second 

Impingement mist eliminator, and a 2-1nch-th1ck fiberglass blanket. 

Each scrubber is 4.88 m (16 ft) high and 2.74 m (9 ft) 1n diameter 

and has 1.22 m (4 ft) of "Maspac®" packing. There is a 6-1nch pressure 

drop across each scrubber. The Maspac® packing is made of Saran® (Dow 

Chemical) and has been 1n service since 1975. Prior to 1975, polypropylene was used as a packing material, but this material disintegrated 

and had to be replaced after only 1.5 years. Chromic ad d disintegrates 

certain plastics as well as causing corrosion 1n metal ducts. Parts of 

the control system that come into contact with chromic ad d mist are made 

of titanium or fiberglass-reinforced PVC to withstand the corrosive acid 

attack. 

The scrubber packing is flushed with clean water for 15 minutes each 

week. Condensate from the scrubber and spent water from the water 

Impingement tank are drained to an evaporator extension tank. The 

concentrate from the evaporator extension tank 1s returned to the chromium 

plating tank as makeup solution. Plant personnel estimated that the 

efficiency of chromium utilization at this plant Increased from 10 percent 

to over 90 percent when this recovery system was Installed. 

The scrubber also serves as the cooling device for controlling the 

temperature of the plating bath. The excess heat 1n the plating tank 1s 

transferred to the scrubbing liquid via a I1qu1d/liqu1d heat exchanger. 

The warmed scrubbing liquid enters the scrubber above the tower packing 

and flows by gravity down through the packing. The contaminated air that 

1s drawn from the plating tank enters the scrubber below the tower packing 
AIRFLOW LEGEND 

^iid FLOOR 

10 FAN T 

< . - •. — 

J J 

I VAI'UI'AluK, .1 Kin.1.1 lPLATING TANK 

1st FLOOK 

Figure 1. Schematic of decorative chromium plating tank. 

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and 1s drawn up through the packing by the exhaust fan. The liquid washes 

the chrome contamination out of the air stream and also warms the air 

stream, resulting 1n the absorbtion (evaporation) of 15.1 i (4 gal) of 

liquid 1n to the air stream. This evaporation process cools the scrubbing 

liquid. The cooled liquid 1s recirculated to the heat exchanger and 

reheated. 

The removal efficiency of the control system on one of the tanks was 

tested 1n 1979. A copy of the test report was obtained by EPA during the 

visit. Ports on the Inlet side of the scrubber are still 1n place; 

however, the duct containing ports on the outlet side has been replaced 

since the test was performed. No visible emissions were observed exiting 

the control device. 

D. Conclusions 

Delco 1s representative of a large-size captive shop that performs 

decorative chromium electroplating of automobile bumpers. Suitable test 

ports are located at the inlet to the evaporator/scrubber, the plating 

bath does not contain a fume suppressant, and the amount of work plated 

would generate chromium emissions adequate for testing. Therefore, 1t 1s 

recommended that emission testing be performed at the Inlet of the 

evaporator/scrubber to obtain an uncontrolled emission level for 

decorative chromium electroplating operations. 

V. Reference 

1. Memo from Duletsky, B., MRI, to Vervaert, A., EPA/ISB. May 21, 

1985. Trip report for Chevrolet-Pontlac-Canada Group, Livonia, 

Michigan, pp. 1-5. 

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