This report is being presented through six chapters which cover fairly wide gamut of this technology sub–set. The broad aspects covered in this report are as follows:
Outline of Electroplating and Electroforming
Electroplating is method for electrolytic deposition of a layer of superior quality metal on a substance. It has been one of the principle manufacturing methods adopted for metal finishing. Use of Nickel as plating material is one of the several metals used for plating. However, more than 50% of the commercial metal finishing is by using Nickel.
On the contrary, Electroforming is a process similar to electroplating, but it is ionic fabrication of metal product which is directly used as an end product. I this process, electrolytic deposition of metal is achieved on a conductive removable mould or matrix and subsequently the latter part is released from metal coating to get an end product which is made of thin metal layer. The popular applications being manufacture of Nickel screens used for filtration in sugar plants and seamless perforated rotary printing screens used in textile mills.
Electro-winning or Electro fining is a technique used for electrolytic recovery of metals from solutions or melts containing the metal ions. This technique is used for recovery of metals which has many features common to Electroplating. All electrolysis processes use Nickel based salts. The recycling of Electrolysis solutions can lead to reduction in Nickel consumption through these salts.
Therefore, in this Chapter sufficient coverage has been given to highlighting the processes of electroplating, electroforming, equipments used in these processes, methodologies adopted and the role of various chemicals and operating parameters in these processes.
In addition to this, we have given coverage for various methods of Electroplating as it is pertinent to mention that appropriate choice of plating method can result in significant reduction in relative Nickel consumption.
Treatment of Effluents from Nickel Plating Industry
It is pertinent to mention that the waste Nickel discharged through waste water and sludge from electroplating and electroforming industry in U.S.A., is more than the Nickel consumption in India for this sector of the industry. Due to such significant drain of Nickel, the industry in U.S.A., has made rapid strides in evolving methods or recycling Nickel containing solutions and recovery of metal.
In Chapter II, different concepts of treatment of waste water and sludge from this industry have been mentioned.
These concepts of recycling of sludge are, very selectively, being adopted in industry. The reason being, most of the, electroplating and electroforming industries consider waste of Nickel as essential expense of the process and consider recovery as infractions attempt in comparison to their principal business objectives. The process of recovery has not been well established and compact plants are not available so as to easily put in line with the manufacturing route.
However, few concerns have certainly made strides to establish independent units. These units which to lift sludge and Nickel containing solutions at throw away prices and recover nickel for marketing to users who can accept purity levels of 98% to 99.7%. As is known, Nickel of extremely high purity i.e. above 99.9% is required in anode basket of electroplating and electroforming industries. Back
