輕燒鎂球燒結降鎂，效益更美 Light-burned magnesium balls sinter magnesium reduction, more beautiful

    近年來，鋼鐵行業形勢嚴峻，鐵前成本壓力急劇增加，鐵礦粉質量不斷劣化。為了穩定燒結礦質量，同時進一步降低煉鐵生產成本，首鋼京唐公司經過一系列基礎研究，最終實現了自然鎂燒結，燒結礦品位、強度、粒度、冶金性能和熔滴性能得到改善，并創造了可觀的經濟效益。

　　輕燒鎂球燒結降鎂優勢明顯

　　作為亞太地區高爐的主要爐料，燒結礦一般占高爐結構的60%以上。通常在燒結配料中添加白云石、蛇紋石等含鎂熔劑來提高高爐渣中的MgO含量，以改善爐渣的流動性和脫硫能力，適應爐渣中的高Al2O3質量分數。

　　燒結作為貢獻高爐渣MgO的主要來源，其MgO含量受高爐渣需求和高爐操作習慣所限。日韓高爐渣中的MgO含量控制在3%~5%的水平，而國內大多在7%以上。受此影響，日本新日鐵、韓國浦項光陽和現代制鐵燒結礦的MgO含量在0.7%~1.2%的水平；而國內燒結礦的MgO含量大多在1.6%以上，高的甚至在3.0%以上。甚至有部分研究者認為，燒結中較高的MgO含量有利于燒結礦質量的提高。

　　近年來，大量國內輕燒鎂球燒結研究者呼吁輕燒鎂球燒結降鎂，首鋼京唐走在了實踐的前列。項目組圍繞首鋼京唐開展了燒結過程熱平衡測算、燒結基礎特性測試和高溫共聚焦原位觀察、礦相研究、燒結杯試驗、綜合爐料熔滴性能測試的一系列燒結降MgO實驗室研究。

　　研究發現：

　　降鎂有助于提高燒結礦品位，有助于發展優質鐵酸鈣，提高燒結礦還原性。降低0.5%的MgO，可提高燒結礦TFe含量0.3%以上；在進口礦粉劣化的背景下，調鎂更顯出主動保燒結礦品位的價值。燒結礦品位的提高，有助于形成更多優質黏結相———針狀鐵酸鈣，從而對燒結礦指標和還原性改善有利。

　　降鎂有助于減少熔劑耗熱，從而增加燒結有效熱量。含鎂熔劑在燒結過程中分解耗熱，降低含鎂熔劑配比有助于節能和改善燒結礦質量。燒結礦MgO含量降低0.5個百分點，含鎂熔劑單耗降低14kg/t燒結礦，燒結過程分解耗熱減少了約1%，相當于在燒結熱損失一定的情況下，燒結過程的有效熱量增加1%，從而有利于燒結礦粒度組成的改善。

　　降鎂有助于改善燒結液相流動性，增強燒結黏結效果。燒結基礎特性和高溫共焦設備測試表明：燒結混勻料MgO含量從2.3%降低到0.3%后，液相流動性指數從0.7提高到1.9；與含MgO的方案相比，原位觀察發現不含MgO的方案具有最高的液相流動速度。燒結液相流動性的改善，增強了黏結效果，有利于燒結礦粒度組成的改善。

　　燒結降鎂搭配球團提鎂，在保證高爐渣系穩定的基礎上改善了綜合爐料的熔滴性能。熔滴性能試驗表明，綜合爐料結構從燒結礦1.9%MgO+球團礦0.7%MgO轉變為燒結礦1.5%MgO+球團礦1.7%MgO后，熔滴區間從64℃降低到59℃，最大壓差從1910Pa降低到1590Pa，最終使綜合爐料的S特性值從122.2kPa·℃降低到93.8kPa·℃。

　　工業實踐創造效益

　　基礎研究發現輕燒鎂球燒結降鎂的優勢明顯，而2012年11月首鋼京唐球團生產鎂質球團礦，為燒結降鎂提供了條件。2013年2月開始研究人員在首鋼京唐燒結開展了降MgO工業試驗，取得了如下結果：燒結礦MgO含量從1.8%逐步降到1.5%水平，結合礦粉結構調整，燒結礦品位從55.95%提高到56.48%，2013年9月份后含鎂熔劑在首鋼京唐已基本停配。降鎂后燒結指標改善明顯：燒結礦<10mm比例從20.28%降低到17.85%，還原性從80.15%提高到84.7%，燒結礦熔滴性能顯著改善，燒結礦的S特性值從262kPa·℃降低到87kPa·℃。近年來首鋼京唐燒結礦主要指標如附表所示。

　　經過一年多工業實踐，2014年首鋼京唐燒結礦MgO含量已穩定在1.4%~1.5%的水平，在國內大型燒結廠中處于最低水平，2014年10月份更是進一步達到1.35%。

　　附圖為首鋼京唐燒結廠與國際上燒結廠MgO含量的比較。與部分國際先進廠礦相比，盡管首鋼京唐燒結礦的MgO含量仍略高，但已屬于不配加含鎂熔劑的自然鎂燒結礦。

　　據統計，首鋼京唐燒結降鎂的年效益達到812.5萬元。2014年10月經過專家鑒定，首鋼京唐燒結降鎂研究及實踐達到國內領先水平。

　　專家認為，首鋼京唐燒結降鎂成功實踐在國內具有較大的應用前景。鋼鐵企業主要可以考慮如下兩種應用方案：一是通過降低燒結礦MgO含量來適當降低高爐渣中MgO含量，為高爐精料做出貢獻；二是降低燒結含鎂熔劑配比，相應地在球團中添加適宜的含鎂添加物———將燒結礦MgO含量轉移到球團中，通過生產低鎂燒結礦和高鎂球團礦來改善綜合爐料的冶金和熔滴性能，進而改善高爐技術經濟指標。

In recent years, the situation of the iron and steel industry has been 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.

優勢 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.

Industrial practice creates benefits

Basic research found that the advantages of light-burned magnesium balls for sintering magnesium are obvious. In November 2012, Shougang Jingtang pellets produced magnesium pellets, which provided conditions for sintering magnesium reduction. In February 2013, researchers began an industrial test of reducing MgO at Shougang Jingtang Sintering, and achieved the following results: The sintered ore MgO content gradually decreased from 1.8% to 1.5%, combined with the ore powder structure adjustment, the sintered ore grade was 55.95% It increased to 56.48%. After September 2013, magnesium-containing flux had been basically stopped in Shougang Jingtang. After magnesium reduction, the sintering index improved significantly: the proportion of sintered ore <10mm decreased from 20.28% to 17.85%, the reducibility increased from 80.15% to 84.7%, the droplet properties of sintered ore improved significantly, and the S characteristic value of sintered ore decreased from 262kPa To 87kPa · ° C. The main indicators of Shougang Jingtang Sinter in recent years are shown in the attached table.

After more than one year of industrial practice, MgO content of Shougang Jingtang Sinter has stabilized at the level of 1.4% to 1.5% in 2014, the lowest level among large domestic sinter plants, and it reached 1.35% in October 2014.

The picture shows the comparison of MgO content between Shougang Jingtang Sintering Plant and international sintering plants. Compared with some international advanced factories and mines, although the MgO content of Shougang Jingtang sinter is still slightly higher, it is already a natural magnesium sinter with no magnesium-containing flux.

統計 According to statistics, Shougang Jingtang's annual sintering magnesium reduction reached 8.125 million yuan. In October 2014, after expert appraisal, Shougang Jingtang sintering magnesium reduction research and practice reached the domestic leading level.

Experts believe that the successful practice of Shougang Jingtang sintering magnesium reduction has great application prospects in China. Iron and steel enterprises can consider the following two application schemes: one is to reduce the MgO content of the sintered ore to appropriately reduce the MgO content in the blast furnace slag to contribute to the blast furnace concentrate; the second is to reduce the proportion of the sintered magnesium-containing flux, correspondingly in the ball Appropriate magnesium-containing additives are added to the pellets--the MgO content of the sintered ore is transferred to the pellets, and the metallurgical and molten droplet properties of the comprehensive charge are improved by producing low-magnesium sintered ore and high-magnesium pellets, thereby improving the technical and economic indicators of the blast furnace .