Method of utilizing pyritic slag to prepare battery grade anhydrous ferric phosphate

Abstract

The invention discloses a method of utilizing pyritic slag to prepare battery grade anhydrous ferric phosphate. The method comprises following steps: introducing hydrochloric acid containing washing water generated in ferric phosphate production into an electrolytic tank to obtain chlorine gas; introducing chlorine gas into yellow phosphorus water, absorbing chlorine gas by yellow phosphorus so asto obtain a mixture of phosphoric acid and hydrochloric acid; and reacting the mixture with pyritic slag to obtain a coarse product of ferric phosphate. Hydrochloric acid in primary washing water iselectrolyzed, chlorine ions are converted into chlorine gas, chlorine gas reacts with yellow phosphorous water to generate a mixture of phosphoric acid and hydrochloric acid, the mixture reacts with pyritic slag to generate a coarse product of ferric phosphate, the pyritic slag is converted into valuable resources, the discharge of chlorine ions is avoided, the environment is protected, positive ions are combined with hydroxyl radicals to generate precipitates, the continuous increasing of positive ion concentration is avoided, the primary washing water can be reutilized in cycle after an electrolysis treatment, the zero discharge of washing water is realized, at the same time, hydrochloric acid can be repeatedly used, and zero discharge of chlorine ions is achieved.

Description

technical field [0001] The invention relates to the technical field of ferric phosphate preparation, in particular to a method for preparing battery-grade anhydrous ferric phosphate by using sulfuric acid slag. Background technique [0002] Iron phosphate can be used as an iron source for the preparation of lithium iron phosphate, the cathode material for lithium-ion batteries, but its cost is relatively high, and iron phosphate alone accounts for nearly half of the cost of raw materials. The cost of iron phosphate must be greatly reduced to meet the needs of the market with high cost performance need. Sulfuric acid slag is the residue discharged after pyrite roasting to extract sulfur. Iron is the main available component in cinder. At present, the comprehensive utilization of sulfuric acid slag is not ideal. Except for a small part used as ironmaking and building materials, most of them are disposed of in landfill, resulting in waste of resources and environmental pollut...

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Problems solved by technology

Using this method to treat hydrochloric acid in waste water has high treatment cost and low recovery value, and also produces a large amount of waste water, which pollutes the environment. Direct discharge not only causes waste of resources, but also has a certain impact on the environment, especially the impact of chloride ions on the environment. The pollution of iron phosphate is particularly prominent. Iron phosphate contains a certain amount of free water and crystal water. The usual treatment method is to use flash drying first, and then use electric furnace to bake. This method has slow production speed and high power consumption for baking.

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