The Study And Process Design For Preparation Of Chromium Formate

Chromium formate is a new type of high pH chrome tanning agent without pickling, more and more getting the favour of people in the field of electroplating. At present, the method of preparing the chromium formate is reducing chromic anhydride by formaldehyde then joined formic acid, that is widely used in China. But the production cost of the process is a little higher, and raw material is toxic. Thus, it is important to explore the chromium formate of low cost, high quality and non-polution.A new process to produce chromium formate is introduced based on experiment by using sodium dichromate and sodium sulfate as the raw material. The optimum process condition are:n (sodium sulfite):n (soduim dichromate)= 3.4:1, n (sodium hydroxide):n (chromium)=2.9:1, n (formic acid):n (chromium)=5.9:1, consumption of washing water is 60mL, reduction temperature is 70 ℃, complexation temperature is 90-95℃, drying temperature is 60℃. The quality under the optimal condition is better than that of industrial product quality, the purity reaches 99%. Circulating the mother liquor which has been concentrated slowly under the control temperature can make the yield reach 90%.The process design of chromium formate takes place after the experiment.First of all, material balance of the total flow and energy balance of. representative equipment are completed. Secondly, the list of the equipments is getted after type-choosing for standard equipments and process calculation for non-standard equipments. Thirdly, this paper gives the control scheme for typical equipment in unit operations of chemical engineering, and the design for pipe. On the basis of above, the piping and instrumentation diagram (P & ID) is accomplished. Finally, workshop equipment layoutment and piping layoutment for the process are present after P & ID.