Method for preparing sodium chromate by mixing chromite and ferrochrome and device for method

Abstract

The invention discloses a method for preparing sodium chromate by mixing chromite and ferrochrome and a device for the method. The method comprises the following steps: measuring and mixing chromite and ferrochrome with sodium carbonate, sodium nitrate and sodium peroxide; pelleting the mixture with extracted liquid sodium chromate in a pelletizer; drying in a drier; returning part of the clinker to a flame kiln after the material is dried and cooled, so that chromite and ferrochrome are decomposed and oxidized in the form of fused liquid phase in molten salts so as to obtain the clinker of sodium chromate; and continuously soaking, filtering and cleaning after the clinker is cooled so that a chromium chemical primary product of liquid sodium chromate is obtained, wherein the flame kiln comprises a U-shaped kiln body, a partition wall and a low-position molten salt suction port, wherein the partition wall and the low-position molten salt suction port are arranged in the U-shaped kiln body; one or more blowing oxygen lances and one or more charging holes are arranged at the top of the kiln body, and a smoke outlet is arranged on the upper side of the kiln; and one or more oxygen lances are arranged at the bottom of the kiln. According to the method disclosed by the invention, the oxidation rate is as high as 98%, the clinker extraction rate is as high as 99.97%, and the chromium yield is 97.96%.

Description

technical field [0001] The invention relates to a method and a device for preparing sodium chromate by mixing chromite and ferrochrome by top-burning oxygen blowing and bottom blowing oxygen again. Background technique [0002] Sodium red alum is related to 15% of commodity varieties in the national economy. It is one of the main varieties of inorganic salts and is widely used in electroplating, tanning, printing and dyeing, medicine, feed, health food, aviation, pigments, catalysts, oxidants and metal corrosion inhibitors, etc. It is listed as one of the eight most competitive resource raw material products. The raw material of sodium red vitriol mainly comes from liquid sodium chromate, a primary product of chromium chemical industry 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 condition...

AI Technical Summary

Problems solved by technology

[0009] Chinese patent (Tianjin Research Institute of Chemical Industry) CN85102681 and CN93112820.X relate to chromite powder and pellet calcium-free roasting, although this patent solves the problem that calcium filler is not added when chromite roasting, and the slag discharge per ton of red alum and sodium is low, but Low production efficiency and serious nodules in the kiln

[0010] Chinese patent (Institute of Process Engineering, Chinese Academy of Sciences) application CN98100556.X uses sodium hydroxide dissolved 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 The alkali mixing rate is high, the equipment is seriously corroded, the obtained sodium chromate alkaline solution contains a lot of free alkali, the content of impurities is high, the post-processing 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 industrialization is difficult. Big

This method is basically similar to the Russian patent RU2096332C1. Although the minimum amount of sodium chromate added is very low, there are more solid phases in the kiln during production. When the amount of chromite is less than 4 times, silicic acid is easily by-produced when the chromite is oxidized. Sodium and more iron slag lead to high viscosity of molten salt, which hinders the oxidation of chromite ore. In severe cases, high viscosity molten salt will block the oxygen lance and cause the kiln to be shut down for maintenance. As a result, the production cost of sodium chromate will increase

At the same time, there are defects in the structure of the kiln. One is that the raw materials in the kiln may be discharged due to short-circuit reasons and the residence time is too short, resulting in a decrease in oxidation rate; the other is that there are dead ends at both ends of the kiln, which will cause insufficient oxidation reaction. , when it is serious, the deposition will affect the discharge

Another is that the bottom gun, side gun, and bottom gun do not consider the coordination with the burning gun, which will cause cold oxygen to directly enter the molten salt, and the oxidation rate will decrease due to the low temperature of oxygen.

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