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OAR Box 1313 

Preppedby LaTeiaShed 

Document Number: 

16) l-B-9 

Docket Number: 

A-88-02 

Printed 6/12/2008 9:03:27 AM Sheet 16 of 99 
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MIDWEST RESEARCH INSTITUTE 

J505 Creeamoor Roao 

Raleign. N.C. 27612 

Teleononei9l9) 781-5750 

A-88-02 

Date: May 20, 1985 

(Finalized November 4, 1985) -

Subject: Site Visit—Modern Hard Chrome Service Company 

Survey of Chromium Emissions Sources—Chromium Plating 

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

MRI Project 7711-L 

From: Barb Duletsky f>^^-

To: Al Vervaert 

ESED/ISB/SSS (MD-13) 

U. S. Environmental Protection Agency 

Research Triangle Park, N.C. 27711 

I. Purpose 

The purpose of the site visit was to gather background information on 

the chromium plating operation at the subject plant and to determine the 

suitability of the plant for chromium emissions testing. 

II. Place and Date 

Modern Hard Chrome Service Company 

12880 East Nine Mile Road .. . 

Warren, Michigan 48089 •"V 

(313) 371-0330 . ' »-- ' Zl I 

March 14, 1985 

;m 181991 

III. Attendees 

Modern Hard Chrome Service Company •-. ' " 

Charles Nicholl, Vice President 

Midwest Research Institute 

Barb Duletsky 

IV. Discussion 

I arrived at the plant at 9:30 a.m. and met with Mr. Nicholl to 

discuss hard chromium plating and emission control techiques. Following 

this, Mr. Nicholl gave me a tour of the Modern Hard Chrome facility, 

during which he provided specific information about the plant. 

' i J 

/ 

Principal Laboratories 425 Volker Boulevard. Kansas City. Missouri 64110 
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A. General 

According to Mr. Nicholl, Modern Hard Chrome is one of the largest 

hard chromium plating job shops in the country. The company has been 

operating at this site since 1952. Presently, there are 75 employees, and 

the plant operates 3 shifts per day, 5 days per week. About 60 percent of 

the company's sales is due to hard chromium plating, and the rest is due 

to-grinding, machining, and electroless nickel plating. 

Hard chromium plating is performed for the automotive industry, the 

steel foundry industry, and various other industries. The plant plates 

items ranging from 17-ft-long industrial rollers to 2-inch-long screw 

machine parts. Items may be plated for any of several reasons: (1) to 

impart specific properties such as hardness, corrosion resistance, and a 

low coefficient of friction to the surfaces of newly manufactured items, 

(2) to correct errors made in machining new items, or (3) to rebuild 

surfaces of used items that have been worn down. 

B. Process 

There are 16 hard chromium plating tanks at this facility, ranging 1n 

capacity from 400 to 3,290 gallons. There is one vertical tank equipped 

with a mechanical hoist used to plate industrial rollers. The rest of the 

tanks are oriented horizontally and are manually operated. The specific 

dimensions of the tanks are shown in Table 1. 

The solution 1n the tanks contains chromic ad d in a concentration of 

30 to 33 ounces per gallon (oz/gal). Sulfuric acid is used as a catalyst 

in a 100: 1 (chromic acid to sulfuric acid) ratio. The plant uses 

60,000 pounds of chromic acid in a typical year. 

Operating parameters are highly variable because of the wide variety 

of items plated. Plating times range from 4 minutes to 4 days, depending 

on the thickness of chromium deposit required, with the average plating 

time being between 5 and 8 hours. The temperature of the plating solution 

is maintained at 125° to 140°F. Each tank is energized by a separate 

transformer/rectifier set. The required voltage in the tanks depends on 

the distance between the electrodes and the items to be plated. As this 

distance increases, the voltage must also increase to overcome the higher 

resistance and maintain the desired current. The electrodes have the 

capacity to draw 3 to 6 volts (V), but usually operate at about 5 V. 

Current 1s a function of the size and shape of the item to be plated. The 

tanks have the capacity to draw 3,000 to 15,000 amperes (A), although the 

operating current is usually between 5,000 and 10,000 A. 

Mr. Nicholl explained that higher current densities increase the 

ability of the steel to attract chromium electrolyte, enabling chromium to 

be plated onto areas that are farther from the electrodes. Figure 1 shows 

the different electrical fields that result when the same current density 

is used to plate three differently shaped surfaces. The exterior corner 

can be adequately plated by applying a current density of 0.5 amperes per 

square foot (A/ft2). In contrast, the interior corner is not adequately 

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TABLE 1. SURFACE AREA OF HARD CHROMIUM PLATING 

TANKS AT MODERN HARD CHROME SERVICE COMPANY 

Tank Surface area, ft 

1 - 28 

2 42 

3 42 

4 44 

5 28 

6 26 

7 16 

007 25 

8 19 

9 19 

10 19 

11 60 

12 36 

14 56 

20 25 

aNote: The solution level is generally 6 inches from 

the blowers along the sides of the tank. Total working 

volume of solution at this plant is 18,700 gallons. 
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EXTERIOR A 

CORNER / 

/ 

/ 

INTERIOR 

CORNER 

CURRENT DENSITY =0. 5 A/ft2 

NARROW 

GROOVE 

7~7 

Figure 1. Electrical fields on three differently shaped surfaces. 

/. 
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plated at this current density because the attraction between the steel 

and the chromium is not strong enough to allow penetration of the chromium 

into the recesses of the corner. Likewise, chromium cannot penetrate into 

a narrow groove because the strong attaction of the steel for the chromium 

at the exterior corners inhibits the passage of chromium into the 

groove. To provide a protective surface on grooved or recessed areas. 

Modern Hard Chrome uses electroless nickel plating. Although nickel does 

not provide the same wear resistance and corrosion resistance as chromium, 

the absence of electrical fields allows for penetration of the plating 

material Into grooved and recessed areas. 

C. Emission Control 

Emission controls on each hard chromium plating tank are similar. An 

example of a typical control configuration 1s shown in Figure 2. 

Emissions from each tank are drawn by an Induction fan through hoods on 

two sides of the tank. Emissions are then forced through a simple 

impingement-type mist eliminator (collector), located on the roof. 

The collectors were designed specifically for this facility by 

Mr. Nicholl's grandfather 1n 1952. Most of the units have been replaced 

twice since then. A typical collector consists of an enclosure, measuring 

5 feet (ft) by 4 ft by 4 ft, housing more than 100 flat metal strips. 

Adjacent rows of metal strips hang at about 120°-angles to each other, 

creating a baffle system on which the add-bear1ng mist Impinges. The 

cleaned gas exits through vents on two sides of the collector, and the 

solution that 1s collected drips back Into the plating bath. 

The collectors appear to provide adequate control of chromium 

emissions, as evidenced by the absence of visible emissions from the vents 

during the visit. The actual control efficiencies of the collectors have 

never been measured, however. The physical design of the collectors 1s 

not suitable for measurement. There are few sections of straight ductwork 

upstream of the collectors and there are no stacks on the collectors. 

Mr. Nicholl noted that emissions cannot be estimated by a mass balance, 

either, because extremely accurate scales are needed to detect the few 

ounces of chromium used to plate a part that weighs 6,000 pounds. 

Mr. Nicholl noted that there are many factors affecting emissions 

from chromium plating tanks. The process itself is highly inefficient, 1n 

that more energy 1s used to generate hydrogen gas than is used to apply 

chromium plate. The degree of visible misting increases as the voltage 

and amperage through the electrodes increase. The surface area of parts 

being plated directly affects emissions because it affects the required 

current. Finally, there appears to be a correlation between the freeboard 

depth (distance from top of solution to hood vent) and the amount of 

solution collected by the control devices. This has not been 

substantiated by actual experimentation, but Mr. Nicholl has noticed that 

increasing the freeboard depth decreases the amount of solution collected 

by the control devices. 

^T 
(FArU 

-7-7-7 / J s / 

f 

M 

7 

\ 

IMPINGEMENT 

MIST ELIMINATOR 

/ /////// / ROOF 

CONTROLLED MIST 

RETURNS TO TANK 

1-1 r-t 

HARD CHROMIUM 

PLATING TANKS 

S / S / / 7 /////////// / FLOOR 

Figure 2. Typical control system on a hard chromium plating tank. 
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D. Conclusions 

The site visit to the Modern Hard Chrome Service Company plant was 

very informative. The plant does not appear to be a good candidate for 

source testing, however. The capture and control devices are in 

satisfactory working condition, but the-configurations are not suitable 

for EPA Method 5 testing. 

7.