Cryolite production process without discharge of waste water

Abstract

The invention discloses a cryolite production process without discharge of waste water, which includes the steps of: 1) preparing slurry; 2) performing reactions; 3) performing centrifugal separation;4) eluting and drying a cryolite crude product separated in the step 3) to prepare a cryolite product; 5) precipitating the cryolite product; 6) alkalizing the cryolite product; and 7) waste treatment: cooling discharged water from an alkalization tank in the step 6) to normal temperature, adding the water into an ammonia separation kettle, adding hydrochloric acid to control content of free ammonia in clear liquid to be less than 1.3%, pH being 6.5-7.1, so that the hydrochloric acid is reacted with the free ammonia (NH3) to generate ammonium chc loride and is reacted with free sodium ions togenerate NaCl, adding ammonium sulfate or ammonium nitrate, as an anionic exciting agent, according to 8-11 wt% of total salt weight, and uniformly adding solid NaCl on the basis of 100% of the content of ammonium chloride to crystallize and separate-out the ammonium chloride under effect of the anionic exciting agent, while the NaCl is rapidly dissolved in water to obtain brine until the ammonium chloride is completely separated out and the brine is saturated, finally performing solid-liquid separation with a centrifuge to obtain the ammonium chloride, the brine returning to the step 2).

Description

technical field [0001] The invention relates to the technical field of mineral preparation, in particular to a cryolite production process without wastewater discharge. Background technique [0002] Cryolite, also known as sodium fluoroaluminate or sodium aluminum fluoride, is mainly used as a flux for aluminum electrolysis; it is also used as a wear-resistant additive for grinding products, which can effectively improve the wear resistance and cutting force of the grinding wheel, and prolong the service life and storage time of the grinding wheel ; Ferroalloy and boiling steel flux, non-ferrous metal flux, casting deoxidizer, olefin polymerization catalyst, and anti-reflective coating for glass, emulsifier for enamel, glass opalescent agent, flux for welding materials, ceramic industry Filling agents, pesticides, pesticides and other industries and enterprises. [0003] Natural cryolite reserves are very small, and most of the cryolite used are artificially synthesized. A...

AI Technical Summary

Problems solved by technology

However, both wet and dry synthetic cryolites have major defects. The intermediate material hydrogen fluoride gas is highly corrosive and toxic, which puts forward high requirements for the selection of production equipment and environmental protection.