轻烧镁粉烧结降镁，效益更美 Light-burned magnesium powder sintering to reduce magnesium, the benefits are more beautiful

近年来，轻烧镁粉钢铁行业形势严峻，铁前成本压力急剧增加，铁矿粉质量不断劣化。为了稳定烧结矿质量，同时进一步降低炼铁生产成本，首钢京唐公司经过一系列基础研究，最终实现了自然镁烧结，烧结矿品位、强度、粒度、冶金性能和熔滴性能得到改善，并创造了可观的经济效益。

　　轻烧镁球烧结降镁优势明显

　　作为亚太地区高炉的主要炉料，烧结矿一般占高炉结构的60%以上。通常在烧结配料中添加白云石、蛇纹石等含镁熔剂来提高高炉渣中的MgO含量，以改善炉渣的流动性和脱硫能力，适应炉渣中的高Al2O3质量分数。

　　烧结作为贡献高炉渣MgO的主要来源，其MgO含量受高炉渣需求和高炉操作习惯所限。日韩高炉渣中的MgO含量控制在3%~5%的水平，而国内大多在7%以上。受此影响，日本新日铁、韩国浦项光阳和现代制铁烧结矿的MgO含量在0.7%~1.2%的水平；而国内烧结矿的MgO含量大多在1.6%以上，高的甚至在3.0%以上。甚至有部分研究者认为，烧结中较高的MgO含量有利于烧结矿质量的提高。

　　近年来，大量国内轻烧镁球烧结研究者呼吁轻烧镁球烧结降镁，首钢京唐走在了实践的前列。项目组围绕首钢京唐开展了烧结过程热平衡测算、烧结基础特性测试和高温共聚焦原位观察、矿相研究、烧结杯试验、综合炉料熔滴性能测试的一系列烧结降MgO实验室研究。

In recent years, the situation of the light-burned magnesium powder steel industry is severe, the cost pressure before iron has increased sharply, and the quality of iron ore powder has continued to deteriorate. In order to stabilize the quality of the sintered ore and further reduce the cost of ironmaking, after a series of basic research, Shougang Jingtang Company has finally achieved natural magnesium sintering. The sintered ore grade, strength, particle size, metallurgical properties and droplet properties have been improved and created Considerable economic benefits.

 Light-burned magnesium sintering has obvious advantages in reducing magnesium

As the main charge of blast furnaces in the Asia-Pacific region, sinter ore generally accounts for more than 60% of the blast furnace structure. Usually dolomite, serpentine and other magnesium-containing fluxes are added to the sintering batch to increase the MgO content in the blast furnace slag to improve the fluidity and desulfurization ability of the slag and adapt to the high Al2O3 mass fraction in the slag.

Rhenium sintering is the main source of blast furnace slag MgO, and its MgO content is limited by blast furnace slag demand and blast furnace operating habits. The content of MgO in blast furnace slag from Japan and South Korea is controlled at the level of 3% to 5%, while most of them are above 7% in China. Affected by this, the MgO content of Japan's Nippon Steel, South Korea's Pohang Gwangyang, and Hyundai Iron Sinter is between 0.7% and 1.2%; while the MgO content of domestic sinters is mostly above 1.6%, which is even higher than 3.0. %the above. Some researchers even believe that the higher MgO content in sintering is conducive to improving the quality of sintered ore.

In recent years, a large number of domestic light-burned magnesium ball sintering researchers have called for light-burned magnesium ball sintering to reduce magnesium, and Shougang Jingtang has taken the lead in practice. The project team carried out a series of sintering MgO laboratory researches on sintering process thermal balance calculation, sintering basic characteristics test and high-temperature confocal in-situ observation, ore phase research, sintering cup test, comprehensive furnace melt droplet performance test around Shougang Jingtang.

The study found:

Magnesium reduction helps to improve the grade of sinter ore, helps to develop high-quality calcium ferrite, and improves the reducibility of sinter ore. Reducing the MgO by 0.5% can increase the TFe content of the sintered ore by more than 0.3%. Against the background of the deterioration of imported ore powder, adjusting magnesium has more value in actively maintaining the sintering ore grade. Increasing the grade of sinter ore will help to form more high-quality binding phases-acicular calcium ferrite, which is beneficial to improving the sinter ore index and reducing property.

Magnesium reduction helps to reduce the heat consumption of the flux, thereby increasing the effective heat of sintering. Magnesium-containing flux decomposes and consumes heat during the sintering process. Reducing the proportion of magnesium-containing flux helps to save energy and improve the quality of sintered ore. The sintered ore MgO content is reduced by 0.5 percentage points, the unit consumption of magnesium-containing flux is reduced by 14kg / t sintered ore, and the decomposition heat consumption during the sintering process is reduced by about 1%, which is equivalent to an increase in the effective heat of the sintering process with a certain sintering heat loss %, Which is conducive to the improvement of the particle size composition of the sinter.

Magnesium reduction helps to improve the liquidity of the sintering liquid phase and enhance the sintering bonding effect. The basic characteristics of sintering and high-temperature confocal equipment tests showed that: after reducing the MgO content of the sintered mix from 2.3% to 0.3%, the liquidity index increased from 0.7 to 1.9; compared with the solution containing MgO, in-situ observation found no The MgO-containing solution has the highest liquid flow rate. The improvement of the liquidity of the sintered liquid phase enhances the bonding effect and is beneficial to the improvement of the particle size composition of the sintered ore.

Sintering magnesium reduction and pelletizing magnesium extraction, on the basis of ensuring the stability of the blast furnace slag system, improved the melt droplet performance of the comprehensive charge. Droplet performance tests show that after the overall charge structure is changed from sintered ore 1.9% MgO + pellets 0.7% MgO to sintered ore 1.5% MgO + pellets 1.7% MgO, the droplet interval is reduced from 64 ° C to 59 ° C, the maximum pressure difference From 1910Pa to 1590Pa, the S characteristic value of the comprehensive charge is finally reduced from 122.2kPa · ° C to 93.8kPa · ° C.