Metal Finishing Industry

Table of Contents  Overview  Regulatory  Planning P2 Programs   Common P2 Practices  Pre-Finishing Operations  P2 in Plating 
P2 in Rinsing  Alternative Methods of Metal Deposition  Facility Design

Table of Contents


List of Figures

List of Tables

Using This Manual

Overview of the Metal Finishing Industry

Types of Shops
Types of Metal Finishing Processes
The Finishing Process
Metal Finishing Demographics
Characterization of the Metal Finishing Industry
Motivations for Implementing Pollution Prevention

Regulatory Overview

Common Wastes from Metal Finishing Operations
   Solid and Hazardous Waste
   Air Emissions
Overview of Federal Regulations Affecting Metal Finishing

Planning Pollution Prevention Programs at a Metal Finishing Facility

   Management Support
   Establishing the Team
Assessing the Facility
   Characterize the Facility
   Gather Baseline Information
   Evaluate the Design of the Facility's Process
Developing a Process Flow Diagram
Identifying Pollution Prevention Opportunities
Analyze and Select Options
   Pilot Test or Validate Preferred Options
   Procure/Implement New System
Keeping the Program Going

Common Pollution Prevention Practices

Employee Training
Housekeeping and Preventative Maintenance
Leak Prevention
Spill Prevention
Inventory Management: Chemical Purchasing, Tracking, Storage, Use, and Handling
Chemical Sample Testing
Maintaining Incoming Water Quality

Pre-Finishing Operations

Assessing the Cleaning Process
   Factors Affecting Cleaning Operations
Cleaning Processes

Pollution Prevention in the Plating Process

General Pollution Prevention Techniques for Plating Solutions
Cyanide-Based Plating Processes
Non-Cyanide-Based Plating Processes
   Chromium Plating
   Nickel Plating
Electroless Plating
Immersion (Displacement) Plating
Chemical and Electrical Conversion
Issues Related to Aluminum Finishing
   Pollution Prevention in Stripping Operations
   Alternatives to Cyanide Stripping

Pollution Prevention in Rinsing

Alternative Rinsing Practices
Alternative Rinsing Methods
   Improving Rinsing Efficiency
   Controlling Water Flow to Rinses
Rinsewater Flow Controls
   Determining the Appropriate Flow Rates
   Methods to Restrict Water Flow
Rinsewater Recycling and Recovery Techniques
Recovery Technologies
   Electrolytic Metal Recovery
Membrane Technologies

Alternative Methods of Metal Deposition

Thermal Spray Coatings
Vapor Deposition Technologies
   Physical Vapor Deposition
   Chemical Vapor Deposition

Design of a Modern Metal Finishing Facility

Process Islands
Rinse Tank Design
Bath Makeup Transfers
Rinse-to-Rinse Transfers
Enclosed Waste Lines
Secondary Containment
Shop Design
Facility Maintenance

Appendix A Glossary

Appendix B Resource List

List of Figures

Figure 1. Markets Served by Metal Finishers—Percent of 1992 Market
Figure 2. Overview of the Metal Fabricating Process
Figure 3. Process for Surface Preparation for Electroplating
Figure 4. Overview of the Metal Finishing Process
Figure 5. Waste Minimization/Pollution Prevention Methods and Technologies
Figure 6. Multiple Reuse of Rinsewater
Figure 7. Overview of the Electroless Plating Process
Figure 8. Illustration of Dragout
Figure 9. Illustration of Drainboards
Figure 10. Three-Stage Countercurrent Rinsing
Figure 11. Example of Reactive Rinsing
Figure 12. Application of Conductivity Cells
Figure 13. Configuration of Rinsewater Recycling in Open- and Closed-Loop Systems
Figure 14. Electrowinning
Figure 15. Two Common Configurations of Atmospheric Evaporators
Figure 16. Illustration of Membrane Flow
Figure 17. Example of Microfiltration Application
Figure 18. Example of Ultrafiltration
Figure 19. Example of Reverse Osmosis
Figure 20. Typical Reverse Osmosis Configuration for Nickel Plating
Figure 21. Two Common Configurations of Ion Exchange
Figure 22. Example of Ion Exchange
Figure 23. Common Ion Exchange Configurations for Chemical Recovery
Figure 24. Example of Process Flow of a Nickel Plating Line Before and After the Installation of Electrodialysis
Figure 25. Typical Acid Sorption Configuration
Figure 26. Typical Ion Transfer Configuration
Figure 27. Configuration of Membrane Electrolysis Application for Bath Maintenance

List of Tables

Table 1. Waste Minimization Options for Metal Plating Operations
Table 2. Process Inputs and Pollution Generated
Table 3. Overview of Federal Regulations Affecting the Metal Finishing Industry
Table 4. RCRA Listed Wastes
Table 5. EPA Regulations for the Three Generator Classes
Table 6. Overview of Assessment Information
Table 7. Alternatives for Chlorinated Solvent Cleaning
Table 8. Precipitators for Common Plating Solutions
Table 9. Alternatives to Cadmium Cyanide -- Product Quality Issues
Table 10. Alternatives to Cadmium Cyanide -- Process Issues
Table 11. Overview of Alternatives for Copper Cyanide Plating
Table 12. Overview of Alternatives for Gold Cyanide Plating
Table 13. Overview of Alternatives for Silver Cyanide Plating
Table 14. Alternatives to Zinc Cyanide -- Product Quality Issues
Table 15. Alternatives to Zinc Cyanide -- Process Issues
Table 16. Immersion Plating Formulations
Table 17. Common Uses of Chromate Conversion Coatings
Table 18. Results of Molyphos as a Substitute for Chromating
Table 19. Overview of Applications for Recycling/Recovery Equipment
Table 20. Overview of Recovery/Recycling Technologies
Table 21. Potential of Metal Using Electrolytic Recovery
Table 22. Overview of Membrane Processes
Table 23. Reverse Osmosis and Specific Metals
Table 24. Overview of Alternative Methods for Metal Deposition
Table 25. Comparison of Alternative Deposition Methods with Conventional Plating

Using This Manual

The Northeast Waste Management Officials' Association (NEWMOA) designed this manual to provide environmental assistance staff with a basic reference on metal finishing. The purpose of the manual is to enable assistance providers to rely on a single publication to jump start their research on pollution prevention for metal finishers with whom they are working. The manual is explicitly designed to be useful to assistance professionals with experience working with metal platers and those who have never encountered metal finishing before. The U.S. Environmental Protection Agency Pollution Prevention Division funded this manual as a model of a comprehensive packet of information on a single industry.

NEWMOA collaborates with state and local environmental assistance programs in the Northeast; these programs have requested this manual to help them provide more efficient and effective help to the numerous metal finishers in the region. Assistance providers have reported frustration with having to search databases for materials only to obtain a list of citations and case studies that they have to spend considerable time finding in order to provide information to their client companies. In addition, these officials rarely have the opportunity to check the accuracy of the information they find in databases to determine whether the material is still current. To avoid duplicating efforts and to ensure that the information platers receive is up-to-date and accurate, NEWMOA developed this manual as a model "synthesized" information packet that includes an exhaustive compilation and synthesis of existing materials on P2 for the metal finishing industry.

To compile this manual, NEWMOA reviewed over 700 books, articles, fact sheets, reports and guides on P2 for metal finishing. NEWMOA staff also sent a draft of the manual to more than 15 expert reviewers for their comments and suggestions. The result is an up-to-date compilation of information on P2 options for metal finishing. However, pollution prevention is a rapidly changing field, and all users should check with the various centers identified in Appendix B to determine whether any new information is available.

The first three chapters of the manual include a statistical characterization of the industry, overview of federal regulations for metal finishing, pointers on implementing process planning and a description of general pollution prevention options. Chapter 4 covers general issues that apply to overall facility operations. Chapters 5 through 7 address specific issues within each process line. These three chapters focus on specific processes, pollution prevention options for these processes, issues pertaining to the options and case studies highlighting the options. Chapter 8 covers alternative deposition processes that replace traditional electroplating operations. Chapter 9 provides information on integrating P2 into a facility's design. In order to reduce redundancy where topics overlap, the text refers the reader to other sections within the document. The manual also has an index to facilitate quick information retrieval. The Appendices provide a glossary and resource listing.


NEWMOA designed this manual for individuals who are involved in providing some form of environmental technical assistance to metal finishing companies. NEWMOA believes that the information in this manual would be useful to environmental inspectors and permit writers that are involved in regulatory compliance activities at metal finishing companies. This manual could help these regulatory officials identify possible pollution prevention opportunities at the firms that they are inspecting or permitting.

NEWMOA designed this manual for assistance providers with little or no experience with metal finishing. NEWMOA suggests that these users pay particular attention to Chapters 1 through 4 to gain a basic understanding of P2 for the industry. Chapters 5 through 9 will become increasingly useful to these users as they work with specific companies on particular issues. To facilitate searching for specific information and topics, the last section of the manual includes an index. NEWMOA expects users of this manual, who are experienced assistance providers to metal finishers, to use only those sections that pertain to their specific situations in client companies. These users may find the information in Chapters 5 through 9 to be the most useful.

As stated above, this is a model for additional manuals that NEWMOA and other regional and national organizations are developing for other industry groups. NEWMOA is interested in obtaining comments and suggestions from manual users on its content and format. Please take a moment and complete the evaluation form at the end of the document to help us with future versions of this and other manuals, or call NEWMOA at (617) 367-8558 ext. 304 and talk with us about the manual.


NEWMOA is indebted to the U.S. Environmental Protection Agency's Office of Pollution Prevention for its support of this project. The Northeast states provided additional in-kind support.

NEWMOA would also like to thank those who provided advice and assistance, especially those who volunteered on the peer review committee:

Mark Arienti, Maine Metal Products Association
Daryl Beardsley, Beardsely & Associates
Bob Brown, ConnTAP
Jim DeWitt, GZA Environmental
Chris Ford, Plating for Electronics
Peter Gallerani,
Gene Park, Rhode Island Pollution Prevention Program
Jackie Peden, Waste Management and Research Center
Karen Thomas, Toxics Use Reduction Institute

Project Staff/Contributors

Lisa Regenstein, NEWMOA P2 Project Manager—Researcher/Author
Terri Goldberg, NEWMOA P2 Program Manager—Managing Editor
Jennifer Shearman, NEWMOA P2 Staff—Editor/Copy Editor
Beth Anderson, EPA—EPA Project Manager
Laurie Case, Waste Management and Research Center—Formatting and Layout

Northeast Waste Management Officials' Association

The Northeast Waste Management Officials' Association (NEWMOA) is a non-profit, nonpartisan, interstate governmental association. The membership is composed of state environmental agency directors of the hazardous waste, solid waste, waste site cleanup and pollution prevention programs in Connecticut, Maine, Massachusetts, New Hampshire, New Jersey, New York, Rhode Island, and Vermont.

NEWMOA's mission is to help states articulate, promote and implement economically sound regional programs for the enhancement of environmental protection. The group fulfills this mission by providing a variety of support services that facilitate communication and cooperation among member states and between the states and EPA, and promote the efficient sharing of state and federal program resources.

NEWMOA was established by the governors of the New England states as an official interstate regional organization, in accordance with Section 1005 of the Resource Conservation and Recovery Act (RCRA). The organization was formally recognized by the U.S. Environmental Protection Agency (EPA) in 1986. It is funded by state membership dues and EPA grants.

NEWMOA established the Northeast States Pollution Prevention Roundtable (NE P2 Roundtable) in 1989 to enhance the capabilities of member state environmental officials to implement effective source reduction programs. The NE P2 Roundtable's program involves the following components: (1) managing a regional roundtable of state pollution prevention programs; (2) publishing a newsletter; (2) managing a clearinghouse of books, reports, case studies, fact sheets, notices of upcoming meetings and conferences, and a list of P2 experts; (3) organizing training; and (4) conducting research and publishing reports and other documents. The clearinghouse provides pollution prevention information to state and local government officials, the public, industry, and others. Funding for the NE P2 Roundtable is provided by the NEWMOA member states and the U.S. EPA. For more information contact: Terri Goldberg, NEWMOA, 129 Portland Street, 6th floor, Boston, MA 02114, (617) 367-8558 x302 (Phone); (617) 367-0449 (Fax); NEPPR@TIAC.NET (e-mail).

The views expressed in this manual do not necessarily reflect those of NEWMOA, US EPA, WMRC, or the NEWMOA member states. Mention of any company, process, or product name should not be considered an endorsement by NEWMOA, NEWMOA member states, or the US EPA.