Plating industry

The use of drip pans to catch products, in cases such as a dairy or ice-cream manufacturing plant, instead of flushing this material to the sewer, considerably reduces the organic load. A similar case exists in the plating industry where a drip pan placed between the plating bath and the rinse tanks win reduce the metal dragout. 

One indicator of business in the plating industry is anode sales to electroplaters however, anode costs ate only a varying portion of the prices used by electroplating shops, because no standard pricing practice seems to exist. The total value of the plating industry is estimated to be in the area of several biUion doUars. Job shop plating sales could be about a biUion doUars. 

Detoxification of chromic acid and chromium salts from the plating industry Use of sulphite Sulphur dioxide... 

The use of electrodeposited metals to protect corrodible basis metals from their service environments has been well established for many years and accounts for by far the larger part of the activities of the plating industry. There are many reasons for using an electroplated metal finish in preference to an organic finish or to making the articles concerned from inherently corrosion-resistant materials. 

Nickel sulfate can be produced from either pure or impure sources. The pure source involves the reaction of pure nickel or nickel oxide powder (combined or separately) with sulfuric acid to produce nickel sulfate that is filtered and crystallized to produce a solid product. The impure raw material may be spent industrial liquor that contains a high percentage of nickel sulfate. The impurities in the liquor are precipitated by sequential treatment with oxidizers lime and sulfides can later be filtered out. The treated liquor, which is a pure solution of nickel sulfate, can be packaged in a drum or further crystallized and dried to produce solid nickel sulfate. Nickel sulfate is used mainly in the metal plating industries. Other uses include dyeing and printing of fabrics and production of patina, an alloy of zinc and brass. 

In a centrally located recovery plant for the treatment of oxidic and hydroxidic metal containing waste (dust and sludge) from steel and metal works, including the plating industry, the main problem is the dominating amounts of iron. To avoid a secondary waste problem, special precautions have to be considered to create an iron product. One possibility is a pyro-metallurgical treatment to produce pig iron or a master alloy. 

In most countries, solid waste containing metals such as neutralization sludge from the plating industry and flue dust from the metal and steel industries is currently collected and dumped in landfill, where it constitutes a perpetual toxic threat to the environment and a waste of resources. The alternatives to this landfill disposal are either to reduce the rate of discharge at source by an individually designed recovery process or to separate and recover the metals from the collected waste in a centrally located facility. A presumption for a centrally located facility would be that companies with metals in their effluents require treatment of their total wastewater streams. This could be accomplished through the relatively simple process of neutralization, which requires minor investment in sedimentation tanks and dewatering equipment and involves relatively modest operation costs. 

Historically, refinery cyanide control was not a concern because cyanide levels in refinery effluent were usually much lower than those in wastewaters from metal finishing and plating industries. Regulatory agencies have now established new and more stringent cyanide effluent limits for most wastewater discharges. One example is the cyanide effluent limit of 0.025 mg/L (as total cyanide) in the San Francisco Bay imposed by the California Water Resources Control Board [60]. 

The lARC has concluded that there is sufficient evidence in humans for the carcinogenicity of chromium(Vl) compounds as encountered in the chromate production, chromate pigment production, and chromate plating industries. In experimental animals there is sufficient evidence for the carcinogenicity of calcium chromate, zinc chromates, strontium chromate, and lead chromate. ... 

Information on nickel exposure from hazardous waste sites is lacking. The most probable route of exposure from hazardous waste sites would be dermal contact, inhalation of dust, and ingestion of nickel-contaminated soil. Groundwater contamination may occur where the soil has a coarse texture and where acid waste, such as waste from plating industries, is discarded. People using this water may be exposed to high levels of nickel. 

In 1996, costs for SLM technology treatment of a wastewater system typical of that found in the nickel-plating industry were compared to those for reverse osmosis treatment of the same amount of wastewater. It was assumed that wastewaters would be processed at a feed rate of 30/gal min, 15 hr/day, and 20 days/month. It was also assumed that a total of 175 lb of nickel sulfate, 45 lb of nickel chloride, and 225 lb of chromium salts would be removed. 

Meltzer, M. P. 1989. Reducing Environmental Risk Source Reduction for the Electro-Plating Industry. Doctoral Dissertation for School of Public Health, University of California, Los Angeles. 

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