Method for comprehensively utilizing low-grade phosphate ores

Abstract

The invention discloses a method for comprehensively utilizing low-grade phosphate ores. In the traditional method, acid phosphate is used as a catalyst to participate in a reaction and used for removing iron and recovering iron hydroxide and phosphate radicals, the investment is increased because novel working sections and equipment are additionally provided in the process, and in addition, the liquid-solid separation process is more difficult because the iron hydroxide is a colloid. The method comprises the following steps of: carrying out ball-milling treatment on nickel laterite ores and low-grade phosphate ores in respective ore grinding systems; mixing the obtained nickel laterite ores and low-grade phosphate ores and concentrated hydrochloric acid with the mass percentage of 20-35%, and carrying out leaching reaction; carrying out solid-liquid separation on the obtained leaching residues and leaching liquid in a filter press, wherein the residue cleaning process is also carried out in the filter press; and mixing a cleaning solution and the leaching liquid, settling by using lime milk to obtain chromium, and then, carrying out a nickel settlement reaction and a magnesium settlement reaction by using the lime milk. According to the invention, the characteristics of components of the phosphate ores and the nickel laterite ores are reasonably utilized, and the comprehensive utilization of the leaching residues of the nickel laterite ores is realized.

Description

technical field [0001] The invention relates to the field of nonferrous metal hydrometallurgy, in particular to a method for comprehensively utilizing low-grade phosphate rock. Background technique [0002] At present, the methods of wet treatment of low-grade phosphate rock at home and abroad are mainly as follows: first, carry out flotation and enrichment treatment on low-grade phosphate rock, so that the P in the mineral material 2 o 5 The content is increased from less than 25% in the raw ore to more than 30%, and then sulfuric acid and phosphate rock are used as raw materials for leaching reaction to generate phosphoric acid leachate and calcium sulfate-containing leaching residue (commonly known as phosphogypsum). The phosphoric acid-containing leachate is purified Refined phosphoric acid or phosphate products can be obtained after purification, and the phosphogypsum is stored and disposed of. Since the existence of a large amount of phosphogypsum poses a threat to th...

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Problems solved by technology

[0005] (1) Atmospheric pressure sulfuric acid leaching method: This method uses sulfuric acid as the leaching agent, controls certain liquid-solid ratio, acidity, temperature and other reaction conditions, and extracts nickel, cobalt, iron, magnesium and other metals from the ore under normal pressure. Leaching; then add neutralizer (limestone, calcium hydroxide, or other alkaline substances) to remove impurities such as iron, aluminum, silicon, etc., and obtain nickel sulfate solution and scrap slag after the impurity-removing slurry is press-filtered, and the scrap slag is washed Outward discharge, the nickel sulfate solution uses sodium hydroxide (or calcium hydroxide, magnesium hydroxide) for nickel precipitation reaction; the obtained nickel slag is acid-dissolved, extracted and impurity-removed to obtain nickel-cobalt deep-processed products; after nickel precipitation, the liquid evaporates Recover magnesium sulfate by crystallization, or directly add alkaline substances (limestone, calcium hydroxide, sodium carbonate, etc.) The recovery rate of metal and magnesium is low, the consumption of acid and alkali is high, and the amount of slag is large and cannot be comprehensively utilized, resulting in high production costs

[0006] (2) High-pressure sulfuric acid leaching method: This method uses sulfuric acid as the leaching agent, controls a certain reaction temperature, and treats laterite ore under pressure; the pressure acid leaching process first began in Cuba in the 1950s. (MOA), since the 1990s, pressured acid leaching plants in Australia, such as Mullin-Mullin, Bloom, and Covas, have been put into operation one after another, but there have been many problems in terms of process and equipment. The basic process of this process is ore After crushing and pulping, enter the autoclave for acid leaching at high pressure (4-5MPa) and high temperature (230-260°C). After leaching, liquid-solid separation is carried out, and then the leaching liquid is neutralized and iron is removed. After iron removal, the liquid is extracted. Nickel-cobalt separation can be further smelted to obtain different nickel-cobalt products according to different needs; the recovery rate of nickel-cobalt in this process can reach more than 90%, but the investment cost of this process is high, and the requirements for equipment and materials are relatively strict. Impurities have a great influence on the consumption of sulfuric acid, so this process is suitable for processing laterite nickel ore containing less than 10% magnesium, especially less than 5%; in addition, during the operation of this process, equipment is prone to fouling, which has a great impact on production. The existence of a series of problems, and the high cost of equipment maintenance, and the inability to use slag reasonably, have affected the large-scale application and promotion of this method to a certain extent.

[0007] (3) Reduction roasting-ammonia leaching method: The reduction roasting-ammonia leaching process was invented by Professor Caron, so it is also called the Caron process, in which NH is used in the ammonia leaching process 3 and CO 2 The nickel and cobalt in the roasted ore are converted into ammonia complexes and enter the solution. The advantage of this process is that the reagents can be recycled and the consumption is small. The disadvantage is that the recovery rate of nickel and cobalt is low, and the recovery rate of nickel and cobalt is 75% and 60% respectively. left and right, and because the mineral materials need to be dried and roasted, the energy consumption is relatively large, and the comprehensive recycling of resources cannot be realized

The alkali source used in the whole process is sodium carbonate. Even if part of the magnesium oxide is used as alkali in the process, the alkalinity comes from sodium carbonate, and the cost of alkali auxiliary materials is high; the process uses acid phosphoric acid Salt is used as a catalyst to participate in the reaction. Since acid phosphate is a chemical product, the purchase price is relatively high, resulting in high cost of production auxiliary materials; this process uses acid phosphate to remove iron and recover iron hydroxide and phosphate. This process adds new Due to the fact that ferric hydroxide is a colloid, the liquid-solid separation process is relatively difficult, which will cause inconvenience in the production implementation process; this process carries out evaporation and concentration recovery of sodium products, due to the addition of sodium sulfate and other series products The value is extremely low, and the concentration in this system is also low, and the recovery by evaporation and concentration needs to be evaluated in terms of economy; in summary, there are still certain problems in the industrial application of this method

[0010] The choice of acid source and alkali source in the hydrometallurgy process of laterite nickel ore: in the choice of acid source, sulfuric acid is mostly used as the acid source, and in the choice of alkali source, sodium alkaline salt (sodium carbonate, hydroxide Sodium, etc.), Chinese Patent Application No. 201210202583.7 discloses a method for comprehensive recovery of valuable metals from laterite nickel ore. This method uses sulfuric acid as the acid source and milk of lime as the alkali source. This acid-base source selection The disadvantage is that calcium sulfate is more or less entrained in the products of using lime milk to collect chromium, using lime milk to deposit nickel, and using lime milk to deposit magnesium. The adverse effects of the existence of this part of calcium sulfate are as follows: Aspects: one is that the purity of the product is reduced, and the other is that calcium sulfate dissolves into the leachate during the acid dissolution process, and the calcium ions in it will subsequently scale in the extraction and other sections, which will have a great impact on the process

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