Rare earth concentrate in the rare earth, generally insoluble in water carbonate, fluoride, phosphate, oxide or silicate and other forms. Must be through a variety of chemical change to rare earth into soluble in water or inorganic acid compounds, after dissolving, separation, purification, concentration and calcination process, made all kinds of mixed rare earth compounds such as mixed rare earth chloride, as a product or separation of single rare earth materials, such a process known as decomposition, also known as rare earth concentrate before processing.
There are many ways to decompose rare earth concentrate, which can be generally divided into three categories: acid, alkali and chlorination. Acid decomposition is divided into hydrochloric acid decomposition, sulfuric acid decomposition and hydrofluoric acid decomposition. Alkali decomposition is divided into sodium hydroxide decomposition or sodium hydroxide melting or baking soda. Generally according to the concentrate type, grade characteristics, product scheme, facilitate the recovery and comprehensive utilization of non-rare earth elements, conducive to labor health and environmental protection, economic and reasonable principles to choose the appropriate process.
Production of rare earth carbonate and rare earth chloride:
These are the two most important primary products in the rare earth industry. Generally speaking, there are currently two main processes for producing these two products.
One process is concentrated sulfuric acid roasting, which roasts rare earth concentrate mixed with sulfuric acid in rotary kiln. After the roasted ore leaching with water, then the soluble rare earth sulfate into the aqueous solution, called leaching liquid. Then add ammonium bicarbonate into the leaching solution, and the rare earth precipitates as carbonate. After filtration, the rare earth carbonate is obtained.
The other process is called caustic soda process, or alkali process for short. Is usually 60% of the rare earth concentrate with strong alkali stir, melting reaction at high temperatures, the rare earth concentrate is broken down, rare earth rare earth oxide into hydrogen, to remove the alkali cakes are washed and excess sodium salt alkali, then washed the rare earth oxide and hydrogen dissolved in hydrochloric acid, rare earth was dissolved rare earth chloride solution, adjustable acidity to remove impurities, after filtration of the rare earth chloride solution by rare earth chloride concentration crystal is made of solid.