Molten liquid phase roasting method of chromite

Abstract

The invention relates to a molten liquid phase roasting method of chromite. The molten liquid phase roasting method comprises the following step of: performing molten liquid phase roasting on a mixture comprising chromite and optional sodium chromate in a horizontal rotary kiln in the presence of oxygen at 350-1,500 DEG C to obtain sodium chromate, wherein the mixture also comprises one or more of soda, sodium bicarbonate, sodium sulfate and sodium hydroxide; the horizontal rotary kiln comprises a kiln body and two end parts at the two ends of the kiln body; the two end parts are provided with a high-position liquid phase outlet and a low-position liquid phase outlet respectively; the kiln body is provided with an oxygen lance and a feed port; the oxygen lance and the feed port are arranged in a stagger way so as not to be on the same cross section of the kiln body; and a smoke outlet which is positioned on the kiln body is arranged between the high-position liquid phase outlet and one of the feed port and the oxygen lance closer to the high-position liquid phase outlet. According to the method, the chromite is in molten liquid phase in a molten salt system, so that the chromium conversion rate is greatly increased, the yield is increased, and the problem of high probability of wall attachment of a calcium-free roasting process is substantially solved.

Description

technical field [0001] The invention relates to a molten liquid phase roasting method of chromite. Background technique [0002] As a basic chemical raw material, sodium red alum occupies an important position in the national economy and is widely used in chemical industry, light industry, metallurgy, printing and dyeing, machinery, daily hardware and other industries. The raw material of sodium rufite mainly comes from sodium chromate produced by roasting chromite ore. The roasting process of chromite is mainly divided into calcium roasting and calcium-free roasting. Their basic principles are to oxidize and roast chromite ore and soda ash under high temperature conditions to convert the chromium in the ore into water-soluble sodium chromate. [0003] Calcium roasting has a large amount of slag discharge, and the Cr in the slag 6+ The content is high, and it contains the carcinogen calcium chromate, which seriously pollutes the environment. Calcium-free roasting uses se...

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Problems solved by technology

[0009] Chinese patent application publication CN101066779A adopts the hot-mixing calcium-free sodium chromate preparation process, and obtains sodium chromate alkaline liquid through processes such as calcination, hot mixing, slaking, sorting, crushing and leaching. Problems with low wall and chrome ore conversion

Chinese patent application CN98100556.X uses sodium hydroxide molten salt medium to decompose chromite to prepare sodium chromate, and the product is leached in a high alkalinity area. Although this method reduces the reaction temperature, the method has a high alkali ratio and the resulting chromic acid There are many free alkalis in the sodium alkaline solution, the content of impurities is high, the post-treatment process is complicated, and the separation time of impurities is as long as tens of hours. Therefore, the production cost of this method is high and the industrialization is difficult.

As the free space of the kiln is filled with knobs, the charge and flue gas cannot pass through, causing the kiln to stop production

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