Method for melting and digesting free calcium oxide in converter slag

Abstract

The invention provides a method for melting and digesting free calcium oxide in converter slag. The method comprises the steps that SiO2 and molten blast furnace slag are added into the converter slag by serving as calcium stabilizers at the temperature of 1,450 DEG C or above, and melt blending is conducted according to a certain weight proportion, wherein the adding amount of SiO2 accounts for 8%-50% of the amount of the treated converter slag, the adding amount of the molten blast furnace slag accounts for 30%-100% of the amount of the treated converter slag, SiO2 and the molten blast furnace slag can be added in an echelon mode or added simultaneously, and constant-temperature digesting is conducted for at least 5 minutes in each echelon of the digesting process, so that full and uniform mixing is guaranteed, entire melt blending is completed within 30 minutes, and water cooling or air cooling can be adopted as the cooling mode. According to the method, the content of free calcium oxide in the improved molten mixed slag reaches the national standard, w(CaO) / w(SiO2) is moderate, the size stability is good, comprehensive resource utilization of solid metallurgy waste is achieved, and more ways are developed for energy saving and consumption reducing of a metallurgy enterprise.

Description

technical field [0001] The invention relates to the technical field of comprehensive treatment of metallurgical slag in the metallurgical industry, in particular to a method for melting and dissolving free calcium oxide in converter steel slag. Background technique [0002] In recent years, with the rapid development of my country's iron and steel industry, the output of pig iron and crude steel has continued to increase. According to statistics from the National Bureau of Statistics of China, the output of pig iron in 2014 was 713.7478 million tons, and the output of crude steel was 822.3063 million tons. As the by-products of the iron and steel production process—blast furnace slag and converter steel slag, the amount of its generation is also increasing with the increase of pig iron and crude steel output. At present, according to the statistics of scrap iron and steel in China, in 2015, the production volume of blast furnace slag and steel slag was 234.94 million tons an...

AI Technical Summary

Problems solved by technology

Chinese Patent Publication (Announcement) No.: CN102559960 proposes to mix hot converter steel slag and blast furnace slag in a certain proportion to dissolve free basic oxides in converter steel slag, and the modified slag after quenching can meet further use requirements, but the fusion During the digestion process, the iron oxides in the converter steel slag will be reduced to iron by the graphite electrode, which will further cause the slag liquid to dry out, the fluidity will deteriorate, and the melting and mixing digestion time will become longer. Blast furnace slag cannot improve the overall fluidity, resulting in low efficiency of fusion and digestion

And Chinese Patent Publication (Announcement) No.: CN102492792A provides a kind of molten steel slag quenching and tempering modification treatment method, steel slag under the temperature of slag discharge and lime and molten state blast furnace slag are carried out conditioning and tempering modification, can dissipate free oxidation in steel slag Calcium and the composition of the modified slag is similar to that of silicate clinker, but adding lime in order to change the activity of the steel slag will inevitably cause new volume stability problems in the modified slag

Chinese Patent Publication (Announcement) No.: CN101638708 proposes a slagging process for dissolving free calcium oxide in converter steel slag, adding SiO in the later stage of converter blowing 2 Materials (quartz sand, cullet, waste casting sand) or calcium silicate materials (can be low-sulfur blast furnace slag) to replace lime slagging, meet the basic requirements of molten steel smelting, and effectively control the w(CaO) of converter steel slag / w(SiO 2 ), and ensure the fluidity of the slag, visible SiO 2 The introduction of calcium silicate material or calcium silicate material can greatly reduce the content of free calcium oxide in converter steel slag, but in the process of converter blowing, it is necessary to accurately control the amount and order of adding modified materials in each link to ensure the composition of molten steel stability, this link will undoubtedly increase the load of steelmaking, and put forward higher requirements for converter steelmaking