Method for reducing and recovering iron from steel slag and preparing auxiliary cementing material from secondary slag

Abstract

The invention discloses a method for reducing and recovering iron from steel slag and preparing an auxiliary cementing material from secondary slag. The method comprises the following steps: uniformlymixing the converter steel slag, a reducing agent and a component adjusting material, performing melting back under the condition that high temperature forms a reducing atmosphere, performing water quenching cooling, separating the metal iron, drying the secondary slag, and performing grinding to obtain the auxiliary cementing material. The method disclosed by the invention can reduce and recoverthe iron in the steel slag by 80% or more; and the prepared auxiliary cementing material is similar to granulated blast furnace slag powder, technical indexes of the auxiliary cementing material meetrelevant requirements of a standard ''ground granulated blast furnace slag used for cement and concrete'' GB / T18046-2008 in China, and the auxiliary cementing material can be used as a cement mixed material and a concrete admixture. The method disclosed by the invention reduces Fe2O3 and FeO in the steel slag into the metal iron for recovery and utilization, changes chemical components of the steel slag to make the components similar to those of granulated blast furnace slag, improves gelling activity, and realizes overall, high-added-value, and more effective large-scale comprehensive utilization of the steel slag.

Description

technical field [0001] The invention relates to the technical field of converter steel slag disposal and application, in particular to a method for preparing auxiliary cementitious materials from steel slag reduction and recovery of iron and secondary slag. Background technique [0002] In recent years, my country's steel output has been ranking first in the world. In 2016, the output of crude steel reached 808 million tons; the discharge of converter steel slag (hereinafter referred to as steel slag) is about 15-20% of the steel output, and it is discharged at a rate of about 100 million tons every year. It belongs to bulk industrial solid waste. [0003] In fact, steel slag is an available resource. On the one hand, the main chemical composition of steel slag is similar to that of ordinary cementitious materials, containing SiO 2 、Al 2 o 3 , FeOx (the abbreviation of iron oxide), CaO, MgO, can be used in cement, concrete industry; 2 o 3 count), mainly Fe 2 o 3 It ex...

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Problems solved by technology

The purpose of these two patented technologies is to reduce the iron in the molten steel slag and sinter the slag into cement clinker; the former adds iron ore and makes iron in a special reactor, and the equipment and process are more complicated. , the investment is large, and it is difficult to realize industrialization in my country's iron and steel plants; the latter only restores the original iron in the steel slag, and it is carried out in the slag discharge process, only a stirring process is added, but due to the high viscosity of the steel slag, it is very difficult to stir

Cang Daqiang from Beijing University of Science and Technology studied the addition of reducing agent and silicon oxide to prepare glass-ceramics from the secondary slag after reducing iron and extracting molten steel slag. It is not used as a cementitious material, and the reduction and the utilization of residual slag require two processes. respectively; Xiang Changxiang of Beijing University of Science and Technology preliminarily discussed the reduction method to process molten converter slag to recover iron and make cement clinker. Steel slag and alumina powder were mixed and heated to 1650°C in a graphite crucible (which also acts as a reducing agent). ℃, by calculating the mineral phase composition of the residue, it is considered to be close to cement clinker, but the actual mineral phase composition and gelling activity have not been studied; it is pointed out that the reduction conditions—the choice of reducing agent and the degree of reduction are the key factors for the preparation of cement clinker Critical, but not further studied

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