Method for calcining titanium dioxide through expansion drying technique

Abstract

A method for calcining titanium dioxide through an expansion drying technique comprises a feeding step and a calcining step, wherein a metatitanic acid material subjected to filter pressing and expansion drying and with the moisture content of 10-15% is conveyed into a rotary kiln to be calcined; the calcining in the rotary kiln is divided into three stages, each stage accounts for one third of the whole length of the rotary kiln, the temperature of the first stage is controlled to be 500-700 DEG C and the standing time is 1.5-2 hours, the temperature of the second stage is controlled to be 700-850 DEG C and the standing time is 1.5-2 hours, the temperature of the third stage is controlled to be 850-950 DEG C and the standing time is 2-2.5 hours. In the method for calcining the titanium dioxide, a heat source required for expansion drying can be provided by high temperature flue gas of the kiln tail of the rotary kiln, and the rotating speed of the rotary kiln is kept at 0.25-0.33 revolutions per minute. The calcining method provided by the invention can increase the productivity, decrease the energy consumption, and also improve the calcining quality of a product.

Description

Technical field [0001] The invention relates to a titanium dioxide calcining method, in particular to a titanium dioxide calcining method using flash drying technology, and belongs to the field of titanium dioxide production. Background technique [0002] In the sulfuric acid method of titanium dioxide production process, calcination is one of the three most critical processes that determines the quality of titanium dioxide. The calcination process of titanium dioxide is roughly as follows: the hydrolyzed product metatitanic acid removes most of the water through a diaphragm filter press, and is fed into a slowly rotating titanium dioxide rotary kiln with a certain slope (usually 3-5%) by a screw conveyor The kiln tail (also called the feed end or high end) and the combustion chamber at the kiln head (that is, the discharge end or low end) blow clean flames and hot air into the kiln to dehydrate, desulfurize and transform the material. After high-temperature calcination, the mat...

AI Technical Summary

Problems solved by technology

[0003] The existing titanium dioxide calcination process has the following problems: 1. When the metatitanic acid material enters the rotary kiln, the moisture content is 50-55%, and the moisture content is high, resulting in high energy consumption and low output in the calcination process. Generally, energy consumption per ton of titanium dioxide is required 2.8-3 million kcal, The annual output of the rotary kiln is only about 20,000 tons; 2. The calcination of titanium dioxide is gradient calcination, the temperature difference is large, and the product quality is unstable; 3. The temperature of the kiln tail gas is as high as 350-450 ° C. After dust removal, it needs to be sprayed to cool down and discharged to the atmosphere. The heat of high temperature flue gas is not fully utilized