Medium Recirculation And Product Separation In Cleaner Production Process Of Law Mineral With Chromium Based On Alkali Treatment

Sub-molten salt of potassium chromate cleaning process succeeded in solving the key technological difficulties in liquid phase oxidation and alkali-chromium-aluminum separation of key technology, which domestic and foreign similar technology can not solve. But the traditional lye boil is considered as hard to operate,insecure,inefficient and energy consumptive, which becomes a bottleneck in chromate cleaning process. Nickel laterite with high chromium by molten salt activation treatment produces raw leachate, whose components are complicated and difficult to separate, for it contains sodium hydroxide, sodium aluminate, sodium chromate, sodium carbonate and so on.This study means to get the feasibility and optimal working condition by high-efficiency rotating film evaporator inspissating alkali solution instead of the traditional system of alkali solution boil. Chromium and aluminum separation and alkali recirculation in treatment of laterite nickel ores containing chromium can be achieved by evaporation-crystallization, carbonation, caustic, and so forth.(1) 1m2 high-efficiency rotating film evaporator is used to inspissate alkali solution from 30% to 50%. The study focuses on effects of heating temperature, feed flow and vacuum on complete solution concentration, evaporation intensity and total heat transfer coefficient, also gets the parameters of the best working condition.(2) 1m2 high-efficiency rotating film evaporator is used to inspissate impurity purified alkali solution from 50% to 75%-80%. The study focuses on effects of heating temperature, feed flow and vacuum on complete solution concentration, evaporation intensity and total heat transfer coefficient, also optimizes the parameters of the working condition.(3) Based on solubility of sodium carbonate, sodium chromate and sodium aluminate in NaOH and properties of sodium aluminate, rough crystal can be grained by evaporating and crystallizating filtrate and separating salts twice. Chromium and aluminum separation and alkali recirculation in treatment of laterite nickel ores containing chromium can be achieved by evaporation-crystallization, carbonation, caustic, and so forth.