First, Ore Crushing
Concentrating mills in China generally use the three-stage breaking flow of rough break, medium break and fine broke to break iron ore. Rough break is often conducted by gyratory crusher of 1.2m or 1.5m, medium break uses 2.1m or 2.2m standardized cone crusher, and fine broke adopts 2.1m or 2.2m short head cone crusher. The block size of the ore undergone rough break is smaller than 1m, then after medium break and fine break, sifted to be final product with granularity smaller than 12mm and sent to the ore grinding trough.
Second, Grinding Process
The most adopted iron ore grinding process in China is the two-stage ore grinding flow. ,concentrating mills of medium-size and small-size usually adopt one-stage ore grinding flow. As a result of fine grinding and then a new screen technology, in recent years a number of concentrator has been replaced by two three-grinding grinding. Grinding equipment used in general relatively small, the largest ball 3.6m × 6m, the largest rod mill 3.2m × 4.5m, the largest since the mill 5.5m × 1.8m, gravel mill 2.7m × 3.6m.
After grinding the classification is basically the use of spiral classifier. In order to improve efficiency, some hydro-cyclone concentrator to replace the second spiral classifier.
Third, Beneficiation Technology
1.Beneficiation Of Magnetite
Mainly used to select low-grade "Anshan-type" magnetite. Since this ore has strong magnetism and is easy to grind and select, all magnetic separation plants in domestic adopt stage ore grinding flow and multi-stage ore grinding flow. Adopt the former (one-stage ore grinding) for coarse-grain embedded magnetite, and the latter (two-stage or three-stage ore grinding) for fine-graine and micro-grain embedded magnetite (Figure 3.2.23). Developed our own series of permanent magnets so that magnetic separator of the realization of a permanent magnet. 70 since, as in the country to promote the fine magnetite concentrator mill screen and then the new technology, so concentrate grade from 62% to about 66% to achieve the Ministry of Metallurgical Industry 65% concentrate grade requirements.
2.Weakly Magnetic Iron Ore Beneficiation
Mainly used to sorting hematite, limonite, pyrite mirrors, siderite, a false impression or a combination of hematite ore, which is the so-called "Red Mine." Such low-grade ore, cloth inlay fine particle size, mineral composition of the complexity of sorting difficulties. After the 80's, processing technology for magnetic roasting, Wet High Intensity Magnetic Separation, weak magnetic flotation process and the re-election, etc., equipment and new varieties of pharmaceutical research continue to improve, so concentrate grade and metal recovery rates rising. Such as the Anshan Iron and Steel Qidashan Concentrator using weak magnetic - Magnetic - a new flotation process, was an encouraging achievement.
3.Polymetallic Total (With) Mine Health
Mineral composition of such complex and diverse, so the method used, equipment and processes are different, such as the use of anti-Bayan Obo iron ore flotation - multi-gradient magnetic separation, flocculation flotation, weak magnetic - the anti-flotation - Magnetic election, the weak magnetic - are flotation, magnetic separation, such as roasting a different process in order to improve the recovery rate of iron and comprehensive recovery of rare earth oxides. Panzhihua Iron through the magnetic separation was about TFe53% vanadium iron ore, magnetic separation tailings after the election through the weak magnetic sweep - High Intensity Magnetic Separation - re-election - flotation - dry separation to obtain titanium concentrates and sulfur refined cobalt ore, titanium and cobalt recovery. Daye Iron Mine using weak magnetic - Magnetic and flotation, comprehensive recycling iron, copper and cobalt, sulfur and other elements.
Fourth, Pellet Sintering Technology
Sintering technology is the primary means for man-made rich ore. Man-made in 1996 produced a total of 160,956,000 rich t, one of key enterprises 94,859,000 t, accounting for 58.9%, local state-owned enterprises 61337000 t, accounting for 38.1%.
China has achieved a relatively high leve in fine ore sintering technology. Anshan Iron and Steel Company as early as the beginning of the 50's in the sintering machine to successfully sinter produced acidic approach to basic methods of sinter produced in the world's first to make use of lime or lime concentrate fluxes to solve the small problem of sintering.
Sintered pellets also increased the level of equipment, there are a total of 419 Taiwan-sintering machine, the total area of 15522m2, of which: 130m2 sintering machine level and above 22 units, the total area of 4107m2; 24 ~ 129m2 sintering machine of 197 units, the total area of 9387m2; 24m2 is less than 200 of the sintering machine, the total area of 2028m2. 1994 years 2 on 24 in Maanshan Iron & Steel Plant of 300m2 sintering machine, outside of China's Baoshan Iron and Steel in addition to the design, manufacture and construction of the largest modern sintering machine.
Sintering of the country in 1995 the main technical and economic indicators: the use of coefficient of 1.36t / (m2/h), grade of 53.00% sinter, sintering machine operating rate of 80.94% calendar, the sinter a pass rate of 84.92 percent, labor productivity of workers for the 2170t/(h/a).