High-titanium slag selective leaching and quality improvement method

Abstract

The invention provides a high-titanium slag selective leaching and quality improvement method. The method comprises the following steps of (1) crushing high-titanium slag and feeding the crushed high-titanium slag and a sodium hydroxide solution into a high-pressure kettle; (2) introducing oxygen into the high-pressure kettle, conducting heating, stirring and heat preservation and completing alkaline leaching; (3) filtering and separating the material subjected to alkaline leaching and conducting water washing on an alkaline leaching product to obtain an alkaline leaching slag material; (4) feeding the alkaline leaching slag material and hydrochloric acid into the high-pressure kettle, adding crystal seeds, conducting heating, stirring and heat preservation and completing acid leaching; and (5) filtering and separating the material subjected to acid leaching, and conducting water washing and drying on an acid leaching product to obtain high-purity titanium dioxide. Through the method,cyclic utilization of resources can be achieved, no industrial wastewater and waste residues are produced, and green production is achieved.

Description

technical field [0001] The invention relates to the technical field of metallurgy, in particular to a method for selectively leaching and upgrading high-titanium slag. Background technique [0002] Most of the ilmenite in China is used as the raw material for the production of titanium dioxide by the sulfuric acid method, and only a small part is processed into titanium-rich materials; the high-titanium slag is used as the raw material for the production of titanium dioxide, titanium tetrachloride and sponge titanium by the chlorination method. The wide application of titanium, titanium-based alloys and titanium dioxide chloride has led to an increasing domestic demand for high-quality titanium slag, that is, titanium-rich materials; due to the fact that the grade of titanium ore in China is generally not high, and the content and types of impurities in it are relatively high. It is more difficult to purify, and industrial production has not been realized in China; the grade...

AI Technical Summary

Problems solved by technology

[0002] Most of the ilmenite in China is used as the raw material for the production of titanium dioxide by the sulfuric acid method, and only a small part is processed into titanium-rich materials; the high-titanium slag is used as the raw material for the production of titanium dioxide, titanium tetrachloride and sponge titanium by the chlorination method. The wide application of titanium, titanium-based alloys and titanium dioxide chloride has led to an increasing domestic demand for high-quality titanium slag, that is, titanium-rich materials; due to the fact that the grade of titanium ore in China is generally not high, and the content and types of impurities in it are relatively high. It is more difficult to purify, and industrial production has not been realized in China; the grade of high-titanium slag produced in China is too low, and the highest can only reach about 94%, especially the impurity content of silicon, iron, manganese, calcium, magnesium and so on. There is an obvious gap in the titanium slag produced by developed countries; at present, it is still impossible to produce high-quality titanium slag of UGS grade, which seriously restricts the development of China's titanium dioxide and titanium sponge industry; and the existing high-quality high-titanium slag production methods have complex processes, Due to the disadvantages of long process, high energy consumption of roasting pretreatment, and large pollution, it is necessary to develop a green cleaning and upgrading method with low energy consumption, high quality and high titanium slag, and it is also the key to the sustainable development of China's titanium industry.

[0003] At present, the methods of improving the taste of titanium slag to obtain high-quality titanium slag include electrothermal method, roasting pretreatment two-step leaching method (UGS slag), hydrochloric acid leaching method, sulfuric acid leaching method and alkali leaching method; electrothermal method is a mature method. The process is relatively simple and does not produce solid and liquid waste, but the electrothermal method belongs to high-temperature smelting, which mainly removes sulfur, phosphorus, and carbon, which consumes high energy and generates a large amount of low-priced titanium; the two-step leaching method of roasting pretreatment, first Sodium roasting changes the phase composition of titanium slag, and then the impurities can be selectively removed by hydrochloric acid pressure leaching, but the effect of silicon removal is not obvious; sulfuric acid method and hydrochloric acid leaching method are mainly for acid-soluble titanium slag, and the desiliconization ability is not strong, long reaction time, and large investment in pressure leaching equipment; the alkali leaching method mainly includes the "New Process for Sub-Soluble Salt Titanium Clean Metallurgy" proposed by the Institute of Process Engineering, Chinese Academy of Sciences. The molten salt method prepares titanium-rich materials; the process step is to mix titanium slag with sodium alkali, and make the titanium slag and sodium alkali undergo a molten salt reaction under normal pressure and low temperature, and efficiently and selectively convert the titanium in the titanium slag into titanium Iron, calcium, magnesium and other impurity components do not react with sodium alkali and remain in the non-titanium slag phase after hydrolysis and precipitation, so as to realize the effective separation of Ti and other impurities, but the alkali consumption is too large, The requirements for equipment are very high, and there are problems such as difficult separation in the later stage; the patent application number 201510250414.4 proposes to use microwave as a heating method to modify the acid-soluble titanium slag, remove impurities with acid, and calcined to meet the requirements of the production of titanium dioxide by the chlorination method, but This method needs to be equipped with a microwave reactor, which requires a large investment in equipment; in the process of modifying the high-titanium slag, it is necessary to add one or more components selected from sodium carbonate, sodium hydroxide, phosphorus pentoxide, sodium phosphate or diphosphate The hydrogen hinge modifier introduces a variety of impurities, which brings difficulties to the subsequent quality improvement; this method uses sulfuric acid as the pickling solution, which will cause difficulties in the subsequent recovery of waste acid and pollute the environment; at the same time, the calcination process needs to be heated to 900-1000 ℃ has high requirements on equipment and high energy consumption; the patent application number 201510879416.X discloses a three-stage process for preparing high-quality titanium slag, which includes modification of titanium slag, pressure acid leaching and granulation, After ball milling, roasting, filtering and washing, then pressurized acid leaching, mixed with binder and microwave drying to obtain high-quality high-titanium slag; Impurities have an impact on the upgrading process; the patent application number 201410387332.X discloses a method for preparing anatase titanium dioxide by acidolysis of clean titanium slag; this method uses commonly used titanium slag as raw material and mixed roasting with sodium hydroxide After acidolysis with sulfuric acid, metatitanic acid precipitation is obtained by hydrolysis, and high-quality anatase titanium dioxide is obtained after roasting. The process requires repeated roasting and consumes a lot of energy. The acid hydrolysis uses 15-55% sulfuric acid to severely corrode the equipment, and Subsequent waste acid is not easy to deal with, which is more harmful to the environment