Chemical Reduction Process
Chemical reduction is a reaction in which one or more electrons are transferred to the chemical being reduced (reductant) from the chemical initiating the transfer (the reducing agent). Chemical reduction can also be defined as a change in oxidation states where the oxidant (reducing agent) is an electron donor. The reductant is the substance which accepts electrons. The overall reaction is called a reduction-oxidation (redox) reaction.
Chemical reduction as a waste treatment process is an established and well-developed technology. The reduction of hevavalent chromiym’s valence state to decrease toxicity and encourage precipitation is presently used as a treatment technology in numerous electroplating facilities. Major advantages of chemical reduction when used to reduce hexavalent chromium is operation at ambient conditions, automatic controls, high reliability, and modular process equipment, ORP (oxidation-reduction potential) and pH controls and instrumentation, mechanical agitation, adequate venting, and separate tanks for subsequent precipitation and sedimentation. The retention time in the reduction tank is pH dependent but should be at least four times the theoretical time for complete reduction.
(Robert Noyes, Handbook of Pollution Control Process,p.285)
Productional Part Approval Process (PPAP)
Productional part approval process (PPAP) defines generic requirements for production part approval, including production and bulk materials. The purpose of PPAP is to determine if all customer engineering design record and specification requiremtns are properly understood by the supplier and that the process has the potential to produce product consistently, meeting these requirements during an actual production run, and at the quoted production rate. The major elements of PPAP are:
· PPAP process requirements
· Customer notification and submission requirements
· Submission to customer
· Part submission status
· Record retention
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