Method for extracting iron ore concentrate from flyash

Abstract

The invention relates to a method for extracting iron ore concentrate from flyash. According to the technical scheme, flyash undergoes dry magnetic separation in a spiral dry magnetic separator with its magnetic field intensity being 0.3-0.5 T so as to obtain rough concentrate and dry tailings; after addition of water, the rough concentrate is put into a wet magnetic separator with its magnetic field intensity being 0.16-0.2 T to undergo wet magnetic separation so as to obtain wet magnetic concentrate; the wet magnetic concentrate or a mixture of the wet magnetic concentrate and second-stage tailings obtained in a subsequent process is put into a ball mill, water is added and then ball-milling is carried out until granularity of 70-90 wt% of the ball-milling product is less than 0.045 mm so as to obtain fine-ground ore slurry; the fine-ground ore slurry is added into a wet magnetic separator with its magnetic field intensity being 0.06-0.1 T so as to obtain first-stage concentrate; the first-stage concentrate is added into a wet magnetic separator with its magnetic field intensity being 0.04-0.08 T to undergo second-stage weak magnetic separation so as to obtain iron ore concentrate and second-stage tailings; and the second-stage tailings return to the step 3. The method of the invention has characteristics of simple process, low energy consumption, high iron grade of iron concentrate powder and high iron recovery rate.

Description

technical field [0001] The invention belongs to the technical field of fly ash utilization. Specifically relates to a method for extracting iron concentrate from fly ash. Background technique [0002] Fly ash is a dust-like substance collected from the flue gas of pulverized coal boilers, and it is a bulk solid waste discharged from modern coal-fired power plants. As a country that uses coal as its main energy source, China relies on coal-fired power generation for a considerable part of its power supply. At present, the total amount of fly ash produced by coal combustion has exceeded 1 billion tons, and it is increasing at a rate of 80 to 100 million tons per year. my country has become the largest ash discharge country in the world. Poor handling of fly ash will not only pollute the air, soil and water, but also occupy a large amount of land, causing great negative pressure on the social economy and the ecological environment. Therefore, how to turn waste into treasure ...

AI Technical Summary

Problems solved by technology

[0007] Iron removal from high-alumina fly ash (Cao Jian et al. Experimental research on iron removal from high-alumina fly ash. Bulletin of Mineral, Rock and Geochemistry, 2010.3), the fly ash was calcined at 900°C for 2 hours for decarburization, and then the concentration of hydrochloric acid was Under the conditions of 20%, liquid-solid ratio of 5:1, temperature of 80°C and stirring time of 60 minutes, although the iron removal rate reached over 80%, iron minerals were not recovered, and a large amount of acid was consumed.

[0008] "A Method for Efficiently Removing Iron from Fly Ash" (CN201510174024.3) patented technology, this technology sequentially undergoes reduction, magnetic separation, and hydrochloric acid leaching of fine powder of fly ash, although the powdered coal with Fe content less than 0.02% is obtained Ash, but not related to recycling of iron

[0009] The second is that iron in fly ash is recovered as a by-product. Iron ore powder in fly ash is not used as the main product. It is generally recovered through a magnetic separation. The grade of recovered iron ore is not high, and it is difficult to meet the smelting requirements.

But it still contains high gangue minerals, it is difficult to meet the smelting requirements