4.1. Fine grain iron ore beneficiation

global mining enterprises in 2014–2015, the supply of iron ore will be oversupplied. Iron ore prices fell for 4 consecutive years, until 2016, however, from 2016, it reversed again. It rose slightly (Figure 9). Over the past 10 years, iron ore prices have experienced two rounds of highs and lows, and the highest point has surpassed 180 US dollars/ton, while the lows have

Iron ore resources in any country belong to the strategic mineral resources, with the interests of nations, in any country are highly concerned about. With the economic development and social construction of third world countries, the demand for iron and steel resources will inevitably increase the demand for iron ore resources. In the future, the emerging economies in the world will compete for iron ore resources more intensively. The high grade and large reserve mines are occupied by the international mining giants. Besides, international mining giants relying on their strong business base for many years, still in the form of acquisitions, mergers and other forms of global search for high-quality iron ore resources, are still constantly expanding their sphere of influence. China's steel enterprises that want to get highquality mines are very difficult. They missed best time to purchase high-quality mines oversea. In addition, Japanese consortium set malicious difficulties to them. China's steel mills have paid a huge price for this. It mainly include: (A) the acquisition cost is too high. Currently, the average grade of overseas iron ore resource invested by the Chinese side is about 40%. Although its quality is inferior to that of the United States, Europe and Japan, it is still superior to the domestic iron ore [14]. Overseas mines geographical locations are mostly terrible, need to increase a large number of mineral processing, power plants, water and other facilities investment in construction, development and construction costs will inevitably increase [14]. According to the current investment in projects under construction estimates, the first phase of overseas iron ore development projects to build capacity of 10 million tons of investment is about 2 billion US dollars on average; if it is a low grade one, the investment will require nearly 3 billion US dollars, such as the Guinea project, the total investment of the project has now

already broken through 50 US dollars/ton.

Figure 9. Japan's Shinkansen iron ore price index.

14 Iron Ores and Iron Oxide Materials

3.4.5. Obtaining overseas rights and interests mines is difficult

In China, iron ore with hematite grain size of less than 0.045 mm or magnetite grain size of less than 0.03 mm is commonly referred to as fine-grained iron ore [18]. Yuanjiacun Iron deposit and Qidong Iron deposit in Shanxi and Hunan Province, respectively, are the most typical fine grain iron deposits in China. The Taiyuan Iron and Steel Group and scientific research units, who aimed at the Yuanjiacun iron ore recycle and conduct a large number of experimental studies. The original iron ore grade of 31.18%, 0.045 mm particle size accounted for 93.81% of the total ore, they got concentrate iron grade 66.95%, and recovery rate of 72.62%. With this process, the Yuanjiacun iron deposit built a mineral processing plant with annual capacity of 22 million tons by the end of 2012 [19]. Changsha Institute of Mining and Metallurgy proposed a selective flocculation desliming-anti-flotation technology and developed a SA-2 flocculant (for the purpose of fine grain size, complex nature of igneous iron ore in Qidong iron deposit) [20]. At present, the Qidong iron deposit uses this technology to build a beneficiation plant with an annual treatment capacity of 2.8 million tons. Under the conditions of a raw ore grade of 28.36% and a grinding fineness of 0.038 mm (98%), the concentrate iron grade 62.5%, the recovery of 68% have been achieved [18–20]. There are many examples like this. Stage grinding —stage magnetic separation likely is the best process for processing fine-grained magnetite [21, 22]; for fine-grained magnetite-hematite mixed iron ore, weak magnetic—strong magnetic resurfacing—reverse flotation process can obtain the high recovery rate; that sorting fine particles hematite process mainly has strong magnetic—desliming—reverse flotation [23, 24], selective flocculation—reverse flotation [25] and strong magnetic—centrifugal beneficiation [26].

tower mills from Ericsson of Germany for fine grinding of vanadium-titanium magnetite. In July 2013, three tower mills of Dahongshan Iron Ore from Kungang Steel were put into production. In 2013, Ansteel Mining Company purchased six sets of vertical spiral mixing mill manufactured by Metso for the Guanbaoshan Iron Ore Concentrator. Li et al. [30] explored the possibility of further improving the grade of concentrate obtained by magnetic separation at a grinding stage of a large-scale iron ore mine in Shandong Province. He began with the concentration of iron grade of 62.35% with 0.022 mm and access to iron grade greater than 65%. The comparison of mixing mill and ball mill on Shizhuyuan iron deposit, Hunan Province show that: when using a stirred mill, the content of newly formed 0.038 mm granular material is 8.1% higher than that of the ball mill, and the monomer dissociation degree of the mixed mill product is obviously higher than that of a ball mill, and the grade of the refined mill product after magnetic separation

The Chinese Iron Ore Deposits and Ore Production http://dx.doi.org/10.5772/intechopen.76729 17

In recent years, many domestic research units aim for magnetization roasting technology and equipment and carry out a large number of studies. Flash magnetization roasting technology was one of them, which was proposed by Yu and his team [34]. And then this technology was applied to the Daxigou siderite deposit, Wangjiatan magnetite deposit, and Jielong magnetite deposit, where they obtained iron grade more than 55 and 70% of recovery rate. In 2009, Lingbao plant started the pilot construction of flash magnetization roasting project of 50,000 tons per year. In 2012, the Institute of Process Engineering of Chinese Academy of Sciences built the pilot project of annual handling capacity of 100,000 tons of refractory iron ore fluidized roasting. Northeastern University put forward a complex refractory iron ore suspension roasting technology, and designed a laboratory batch suspension roaster. Using the designed roaster, restricted the air velocity, reducing gas concentration, calcination temperature and roasting time were tested on the positive flotation tailings and oolitic hematite of Anshan Iron & Steel Co., Ltd. at Dong'anshan Sintering Plant. Under the best experimental conditions, they got iron grade 56–61% and recovery rate of 78–84% [35]. According to the basic research results, Northeastern University and the Institute of Mineral Utilization of Chinese Academy of Geological Sciences and Shenyang XinBo Industrial Design Co., Ltd., designed and built a 150 kg/h complex refractory iron ore suspension roasting pilot system in Emeishan City. In September 2014, the continuous flotation test was carried out with the positive flotation tailings from the tailings of the East Anshan Sintering Factory and the magnetic separation of the tailings of the Ouzanshan Magnetic Puller tailings. The magnetized roasted products produced by this system, after magnetic separation, reached the grade of

For those beyond conventional processing methods and magnetization roasting technology, the relevant domestic researchers put forward a deep reduction-magnetic separation technology that uses coal as an agent to reduce iron ore minerals to metallic iron below the melting temperature of ore, and then promotes the growth of metal iron particles to a certain size. Deep

is 5.2% higher than after ball mill [33].

4.3. Magnetization roasting technology

concentrate iron 63–65%, and the recovery rate of 78–83%.

4.4. Deep reduction and magnetic separation technology

#### 4.2. Efficient grinding technology

It would be subdivided into: high-pressure roller mill technology, self-grinding/semi-self-grinding technology and stirring mill technology [12]. The high-pressure roller mill technology is highly dependent on ore ultra-fine grinding equipment: high-pressure roller mill. It is a unit of low energy consumption, high handling capacity. Compared with the traditional crushing equipment, high-pressure roller mill pulverized products significantly increase the internal microcracking, ensure high content of fine-grained fraction and mineral dissociation [3, 27–30]. Domestic experts and scholars carried out a great deal of research work on the application of high-pressure roller mill technology in iron ore, and formed the crushing-preselection technology of high-pressure roller mill to maximize the crushing and minimize friction in order to reduce processing costs. Masteel company conducted this technic on low-grade iron ore (including high-pressure roller mill, wet grading, coarse magnetic separation pre-selected tail-polishing technology) in Nanshan iron ore deposit, the annual throughput of the beneficiation plant increased by 2.7 million tons, and the electricity consumption and the consumption of steel per unit ore dropped by about 30% [20]. And then, this technology has been introduced into dozens of iron ore processing plants in Hebei Province such as Sijiaying Iron Mine, Panzhihua Iron Mine in Sichuan and Dachang Iron Mine in Anhui [31]. The grain size, grinding and dissociation characteristics of lean hematite ore after being crushed by a high-pressure roller mill have been studied. Details of this technology are still locked. However, compared with the jaw crusher, the high-pressure roller mill has a high crushing ratio, high content of fine-grained, uniform particle size distribution and the Bond power index decreased by 13.96–28.23%, 0.5 mm grain iron ore monomer dissociation increased by 15.16% [13]. Compared with the conventional three-stage closed-circuit crushing process, the self-grinding/semi-autogenous grinding process has the features of simple process, low capital investment, large-scale equipment efficiency and low dust pollution. At present, China has more than 60 beneficiation plants using more than 160 selfgrinding/semi-autogenous mills. For example, Dahongshan Iron Mine of Kunming Iron and Steel Co., Ltd. has used 8.53 m 4.32 m semiautomatic milling + ball milling + ball milling (SAC) process to crush iron ore from 2006 with the processing capacity of 4 million t/a [1]. Stir mill as a fine to ultra-fine grinding equipment was gradually being applied to the fine-graining of iron mines in China [20, 32]. In 2010, Panzhihua Iron and Steel Co., Ltd. purchased three

tower mills from Ericsson of Germany for fine grinding of vanadium-titanium magnetite. In July 2013, three tower mills of Dahongshan Iron Ore from Kungang Steel were put into production. In 2013, Ansteel Mining Company purchased six sets of vertical spiral mixing mill manufactured by Metso for the Guanbaoshan Iron Ore Concentrator. Li et al. [30] explored the possibility of further improving the grade of concentrate obtained by magnetic separation at a grinding stage of a large-scale iron ore mine in Shandong Province. He began with the concentration of iron grade of 62.35% with 0.022 mm and access to iron grade greater than 65%. The comparison of mixing mill and ball mill on Shizhuyuan iron deposit, Hunan Province show that: when using a stirred mill, the content of newly formed 0.038 mm granular material is 8.1% higher than that of the ball mill, and the monomer dissociation degree of the mixed mill product is obviously higher than that of a ball mill, and the grade of the refined mill product after magnetic separation is 5.2% higher than after ball mill [33].
