Preparation and comprehensive utilization method of magnesium bicarbonate solution

Abstract

The invention relates to a preparation and comprehensive utilization method of a magnesium bicarbonate solution. The method is used to prepare the magnesium bicarbonate solution used for deposition, crystallization and recovery of rare earth ions, and comprehensive recovery of calcium-compound products and magnesium-compound products by taking dolomite as a raw material. The method specifically comprises: roasting dolomite to obtain a powder containing calcium oxide and magnesium oxide, directly mixing with a magnesium chloride solution for digestion and alkali transformation at the same time to prepare a magnesium hydroxide secondary-product and a calcium compound secondary-product, and further to realize effective separation of calcium and magnesium; performing slurry mixing on magnesium hydroxide, introducing carbon dioxide gas for a carbonization reaction to prepare the magnesium bicarbonate solution; applying obtained magnesium bicarbonate to deposition and crystallization of the rare earth ions to produce rare-earth carbonate or rare-earth oxide products; and recycling one part of the filtrate to prepare magnesium bicarbonate, and evaporating one part of the filtrate for crystallization to produce the magnesium compound product.

Description

Technical field [0001] The invention relates to a method for the preparation and comprehensive utilization of a magnesium bicarbonate solution. Specifically speaking, dolomite is used as raw material to prepare pure magnesium bicarbonate solution, which is used for the precipitation and crystallization of rare earth ions to produce rare earth carbonate or oxide products, while comprehensively recovering calcium and magnesium products, which belongs to the field of comprehensive utilization of dolomite. Background technique [0002] Dolomite is a natural mineral composed of calcium carbonate and magnesium carbonate, generally white, off-white and yellow. The chemical formula is CaMg(CO 3 ) 2 , The theoretical molar ratio of calcium to magnesium is roughly 1:1; it also contains a small amount of calcite CaCO 3 And a very small amount of quartz SiO 2 Wait. my country's dolomite resources are very rich and widely distributed. The production areas are all over the country. The main p...

AI Technical Summary

Problems solved by technology

The main problems in this process: ① A large amount of low-value magnesium-containing calcium carbonate is produced. If it is not recycled, about 5.5 tons of magnesium-containing calcium carbonate with a net weight of about 5.5 tons per ton of light magnesium oxide will be discharged to form a paste (nearly 10 tons of waste residue). Cause environmental pollution and waste of resources

②The magnesium oxide content in the heavy magnesium water obtained by the dolomite carbonization method is low, and the water consumption is large, resulting in pyrolysis energy consumption accounting for more than 40% of the total energy consumption, and the production cost is high

The above-mentioned rare earth solutions are usually precipitated with oxalic acid and roasted to obtain rare earth oxides. The product obtained by this method has high purity, but oxalic acid is expensive, the production cost is high, and a large amount of oxalic acid wastewater is produced; some products use ammonia water or ammonium bicarbonate as a precipitant to produce rare earth Carbonates or hydroxides can also be roasted to obtain rare earth oxides, but a large amount of ammonia nitrogen wastewater is produced to pollute the environment. The cost of recycling ammonia nitrogen wastewater is very high, and it is difficult to meet the requirements of environmental protection standards; some companies use sodium carbonate in order to eliminate ammonia nitrogen wastewater pollution. Instead of ammonium bicarbonate or ammonia as a precipitant to produce rare earth carbonates or oxides, but the cost is doubled, and it also brings sodium salt wastewater pollution

Images