Process for roasting chromite resources in ring kiln through pure oxygen by using low-temperature method and harmlessly and deeply utilizing chromium residue

Abstract

The invention belongs to the field of metallurgy and chemical engineering. The process comprises the following steps of: firstly, crushing chromite, adding sodium hydroxide and a catalyst to be oxidized and roasted by using a low-temperature pure oxygen method; diluting, cooling, extracting and filtering to obtain a sodium chromate crystal and ferrum-magnesium slag; adding an alkali washing solution into a sodium hydroxide solution to back extract to obtain the sodium hydroxide solution for recycling; adding water into the sodium chromate crystal and ferrum-magnesium slag to be dissolved and feeding filtrate into a carbonizer to decompose to extract aluminum; carbonizing, evaporating, condensing and crystallizing the extracted solution to obtain sodium chromate; and carbonizing ferrum-magnesium filter slag to generate sodium bicarbonate, reacting to generate a magnesium hydrogen carbonate solution, heating and cracking to generate a magnesium carbonate product and drying a filter cake to obtain ore refined powder; and secondly, crushing chromium residue, adding sodium bicarbonate in the ration of 1:8, adding a catalyst for calcination, cooling and adding water to soak; adding an aluminum hydroxide crystal into supernatant liquid, carbonizing and decomposing to remove aluminum in a reaction tank; filtering and washing an aluminum hydroxide product; adding a reducing agent into the filtrate to reduce hexavalent chromium to generate anhydrous chromium hydroxide and drying and roasting to obtain chromium sesquioxide; and returning the filtrate to a system for mixing after pyrolyzing and extracting to remove magnesium.

Description

technical field [0001] The chromium salt industry is a key industry intersecting inorganic chemical industry and metallurgical materials, and the invention belongs to the technical field of metallurgy and chemical industry. Background technique [0002] Chromium salt and metal chromium are indispensable materials for the development of the national economy. Chromium salt is one of the main varieties of inorganic salts. It is widely used in many important industrial sectors such as chemical industry, metallurgy, light industry, electronic machinery and military industry in various sectors of the national economy. . Mainly used in electroplating, leather tanning, printing and dyeing, medicine, pigments, catalysts, oxidants, matches and metal corrosion inhibitors, etc. According to the statistics of relevant state departments, chromium salt is related to 10% of commodity varieties in our country. Therefore, the healthy development of the chromium salt industry has an influenc...

AI Technical Summary

Problems solved by technology

The conversion rate of chromium in the traditional process of high-temperature calcium roasting is only 70%, and the atomic utilization rate of resources is less than 20%.

For every ton of chromium salt product produced, 2-2.5 tons of highly toxic chromium slag are produced at the same time. The slag contains 7-10% of hexavalent chromium (calculated as red alum sodium), and the contained hexavalent chromium is 1000-10000 times that of the national emission standard; currently The most advanced chromium salt production technology at home and abroad is calcium-free roasting technology, which can reduce the amount of slag to 0.8t / t product, but the slag still contains 0.1% hexavalent chromium, which cannot completely solve the problem of chromium slag pollution