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Jiuquan Iron beneficiation plant mainly deal with its own mines - Iron Mountain mirror Huashugou iron ore and black trench mine, has now reached production capacity of 6.5 million t of iron ore processing. Jing Tieshan iron ore is a typical refractory iron-poor ore, which has the characteristics of low ore grade, complex mineral composition and fine grain size. Iron minerals mainly include specular iron ore, magnesite and limonite. A small amount of magnetite; gangue minerals are mainly jasper, barite , iron dolomite and quartz , and the surrounding rock of the ore body is phyllite.
The original design of Jiugang Concentrator was to treat the Jingtieshan iron ore by full roasting magnetic separation process. During the process evolution, the ore roasting magnetic separation (150～15mm grain size) and fine ore magnetic separation (15～0mm) were gradually formed. The process pattern of the granular grade). The lump ore roasting equipment is a 100m 3 Anshan type reduction magnetization roasting shaft furnace, and the roasting process is closed-circuit magnetization roasting; the grinding process is two-stage grinding, the grinding fineness is -200 mesh accounts for 85%; the sorting process is single weak Magnetic separation, five-stage selection process, in which the first and third selections use dewatering tanks, and other operations are weak magnetic separators. Due to the complexity of the mineral composition, the useful mineral siderite and its secondary change mineral limonite contain low levels of theoretical iron due to impurities such as magnesium, manganese , silicon and aluminum . The main gangue minerals jasper (10.45% iron), iron dolomite (10.56% iron) and surrounding rock iron phyllite (containing 6.7% to 10% iron) are reduced by iron and minerals. The difference makes the beneficiation process difficult, and the original production process is relatively simple, the grinding grain size is coarse, and the iron concentrate quality has been at a backward level. The grade of roasting magnetic separation concentrate before transformation is about 56.5%, the content of SiO 2 +A1 2 O 3 is about 11%, and the grade of strong and weak magnetic comprehensive concentrate is only 52.50% (after deducting the burning loss is 57.00%), resulting in the blast furnace of the wine steel. The grade of the furnace has been in the national countdown for a long time, which has seriously affected the technical indicators and economic benefits of ironmaking.
I. Cationic reverse flotation test study
In order to improve the quality of iron concentrates, Jiuquan cooperated with Changsha Research Institute of Mining and Metallurgy to carry out a large number of researches, which provided a basis for the upgrading and reduction of roasting magnetic separation concentrates (Table 1). In 1997, a mixed amine was used as a collector in the laboratory to complete the reverse flotation test of the magnetic separation concentrate of the wine steel roasting. The preliminary results were achieved. In the first half of 2005, GE-609 was used as a collector in the laboratory. The research on anti-flotation, quality improvement and impurity reduction, the consumption of chemicals decreased drastically, and the foam performance and process index improved significantly. On this basis, in the second half of 2005, the semi-industrial split test of cation reverse flotation was carried out on the secondary magnetic separation concentrate of the concentrator roasting magnetic separation. The remarkable effect was obtained. Under the severe winter and normal temperature conditions, the 72h stability test was carried out. The results show that the index of one rough selection, one selection and four sweeping reverse flotation processes is 61.82% of concentrate grade, 5.46% of SiO 2 content and 93.98% of operation recovery rate. Compared with the production index of single magnetic separation process in the same period, the concentrate iron grade increased by 4.05% and SiO 2 decreased by 4.65%.
Table 1 Results of previous experiments on cation reverse flotation of roasting magnetic separation concentrate
Test time
/a
scale
Collector
Feed mine
grade
Concentrate grade
Tailings
grade
Recovery rate
Increase in the grade of the ore
TFe
SiO 2
1997
2005
2005
Small
Small
Semi industry
Mixed amine
GE-609
GE-609
56.36
55.26
56.53
60.54
60.40
61.82
5.52
5.46
29.81
20.41
24.20
92.81
95.25
93.98
4.18
5.14
5.29
   Second, cationic reverse flotation production practice
According to the results of semi-industrial split test, in 2007, Jiuquan Steel carried out cationic reverse flotation on the roasting magnetic separation system of the concentrator, and improved the process. The modified process was three-stage grinding, four magnetic separation-cation floating The selection process, that is, on the basis of five selections of weak magnetic separation, cancels the fifth selection and introduces the fourth magnetic separation concentrate into the re-grinding-reverse flotation system. The regrind operation consists of a ball mill and a hydrocyclone to form a grinding and grading circuit. The flotation process is a rough selection, a selection, and a four-sweeping reverse flotation process. The renovation project started construction in March 2007, and was completed and put into operation in December 2007. In April 2008, the industrial commissioning was completed and the production reached the standard.
(1) Industrial commissioning results
After the project is put into production, the automatic control and commissioning is first carried out, including automatic control of pumping tank liquid level, automatic control of grinding, automatic control of flotation liquid level, automatic control of concentration, automatic dispensing and commissioning of production execution system (MES). The main process parameters of grinding and flotation were tested and the suitable process parameters were determined. In the case of full production of the concentrator, a continuous 72h stabilization test was carried out on April 26-29, 2008. The results are shown in Table 2. The number of quality process indicators is shown in Figure 1.
Table 2 Industrial production stability test indicators
Indicator category
Iron grade /%
Concentrate containing SiO 2 /%
Flotation operation selection ratio / times
Job recovery rate /%
Grade increase / percentage point
Feed mine
Concentrate
Tailings
Preliminary design indicator
60.50
1.160
94.00
Industrial production stability test indicators
55.76
60.61
24.16
5.76
1.154
94.23
4.85
Fig.1 Quality process of cation reverse flotation number of roasting magnetic separation iron concentrate
Table 2 shows that under the condition of 55.76% of the flotation of the ore grade, the concentrate grade is 60.61%, the SiO 2 is 5.76%, the tailings grade is 24.16%, and the flotation operation recovery rate is 94.23%. Compared with the design index, the concentrate grade and the operation recovery rate all reached the design index; compared with the original single magnetic separation process, the concentrate grade increased by 4.04% after the reverse flotation, and the SiO 2 content decreased by 4.74%.
(2) Production indicators
After commissioning, the process enters the normal production phase. In the past four months, the production process has been stable and the foam transportation has been smooth. Under the condition that the proportion of easy ore is decreasing and the ore selectivity tends to deteriorate, the production index has basically maintained the commissioning level (Table 3).
Table 3 Industrial production indicators
time
Iron grade /%
Concentrate containing SiO 2 /%
Concentrate yield /%
Job recovery rate /%
Grade improvement / (percentage points)
Feed mine
Concentrate
Tailings
April 2008
May 2008
June 2008
July 2008
Average
55.57
55.04
55.55
54.61
55.19
60.01
59.75
60.23
59.96
59.99
23.43
21.75
22.53
22.91
22.66
6.19
6.61
6.17
5.83
6.20
87.76
87.60
87.59
85.56
87.14
94.77
95.10
94.97
93.94
94.72
4.44
4.71
4.68
5.35
4.80
  Third, the advantages and disadvantages of iron ore cation reverse flotation
Production practice shows that the use of cationic reverse flotation of iron concentrates has the following advantages compared to anion reverse flotation:
(1) The pharmaceutical system is simple. The reverse flotation of the wine steel roasting magnetic separation concentrate uses GE-609 as the collector, starch as the inhibitor and sulfuric acid as the adjusting agent. The pharmaceutical system is relatively simple.
(2) Energy conservation. GE-609 is resistant to low temperatures and requires a minimum flotation temperature of 8 °C. The slurry temperature of the above-mentioned semi-industrial split test is 12 ° C, and the lowest temperature of winter pulp in industrial production is above 15 ° C, which fully meets the requirements of room temperature flotation. The anion reverse flotation generally requires the pulp temperature to reach about 30 ° C, and must be heated. Therefore, the use of GE-609 as a cationic reverse flotation collector has significant energy saving effects.
(3) Flotation of weakly alkaline media, the waterway is not fouled. Iron ore anion reverse flotation usually requires the pH of the slurry to be around 11, and CaO is added as an activator to greatly enhance the fouling of the water. The cationic reverse flotation is floated under neutral or weakly alkaline conditions without CaO, and the fouling of the aqueous water is not enhanced. For the wine steel ore, due to the high pH value of the original water, the sulfuric acid is added to reduce the pH before the flotation, and the fouling of the water is reduced.
(4) It has strong adaptability to gangue and good desiliconization effect. The iron ore of the Jigangshan Iron Ore is complex in composition and various in gangue. The desiliconization effect is not good when using anion reverse flotation. GE-609 has a good collection effect on jasper, phyllite, iron dolomite and quartz, and has strong adaptability to gangue and good desiliconization effect.
Of course, things are always divided into two. There is also a disadvantage in the reverse flotation of iron ore cations, that is, the foam is not as brittle as the anion reverse flotation, and the fluidity of the foam is not as good as that of the anion reverse flotation. This is also the problem that everyone often pays attention to. From the production practice of Jiugang, this problem does exist, but it is not so serious. Using GE-609 as a collector, the foam is not as sticky as originally thought. As long as the foam conveying equipment and piping parameters are properly selected, there is no problem in production direct production. The production practice of Jiuquan Steel for more than 8 months fully illustrates this. At one point, this may be related to the performance of the GE-609.
   Fourth, economic benefit evaluation
(1) Direct benefits
Compared with the original process, after upgrading embodiments falling heteroaryl transformation roasting iron ore grade increased 4.04%, SiO 2 4.74 percentage point reduction, produce less SiO 2 10.25 million t per year. The price paid is that the ore processing process consumes 186,100 tons of lump ore, and the processing capacity of flotation operation is 2,154,400 tons. It is necessary to increase the raw material fee and the processing cost of mineral processing to a total of 91.29 million yuan.
The sintering process can save 188,000 tons of limestone and 243,200 tons of sintered ore per year, and the total cost savings of the two joints is 16.42 million yuan. In the ironmaking process, the grade of the blast furnace is increased by 1.57%, the coke ratio is reduced by 13.4kg/t, and the annual coke is saved by 67,000 tons, and the iron is increased by 224,800 tons. The total ironmaking benefit is 170.12 million yuan.
From the beneficiation to the iron making process, the company's overall cost reduction of 95.25 million yuan, the benefits are significant.
(2) Energy saving and emission reduction benefits
1. Energy saving benefits. After upgrading drop heteroaryl embodiment, processing steps increase the annual power consumption of 3142 × 10 4 kW · h, equivalent to the standard coal 38600 T; sintering step due to reduced processing volume and limestone savings can save coal 11600 t, every year due ironmaking Saving coke can save 58,200 tons of standard coal, saving a total of 31,200 tons of standard coal.
2. Emission reduction benefits. Solid waste: After upgrading and reducing impurities, the amount of ore dressing tailings increased by 340,000 tons per year. Due to the significant decrease in SiO 2 content in concentrates, the amount of blast furnace slag decreased by 180,000 tons per year. The two are offset by an increase of 160,000 tons of solid waste.
Sulfur dioxide emissions: Since the sulfur in the concentrate is reduced by 1678 tons, the sintering process can reduce the sulfur dioxide emissions by 2181 tons, and the iron making process can reduce the sulfur dioxide emissions by 1092 tons. Because of the coke saving, the iron making process can reduce the sulfur dioxide emissions by 1099 tons. The three totals can reduce sulfur dioxide emissions by 4372t.
Greenhouse gas emissions: Due to the low consumption of limestone, the sintering process can reduce carbon dioxide emissions by 68,500 tons; due to the saving of coke, the ironmaking process can reduce carbon dioxide emissions by 217,000 tons. Together, they can reduce CO2 emissions by 285,500 tons per year.
Sewage discharge: upgrading and reducing impurities need to increase the tailings wastewater by 784,000 tons. This part of the water is transported to the tailings dam with the tailings and can be reused.
Overall, although solid waste storage has increased, sulfur dioxide and carbon dioxide emissions have decreased significantly. Therefore, the project is beneficial to the environment.
(3) Other benefits
After upgrading and reducing impurities, the content of other impurities in iron concentrates also decreased significantly. Among them, K 2 O is reduced by 1789t per year, Na 2 O is reduced by 678t, S is reduced by 1854t, and P is reduced by 180t. This can reduce the blast furnace alkali load by 0.516kg/t, S load by 0.078 kg/t, and P load by 0.038kg/t. It is beneficial to improve the furnace condition of the blast furnace and reduce the consumption of steel materials.
   V. Conclusion
(1) The Jiugang concentrating plant adopts the cationic reverse flotation process to upgrade the roasting magnetic iron concentrate, improving the grade of concentrate by 4.04% and the content of SiO 2 by 4.74%, from beneficiation to iron making. The cost can be reduced by 95.25 million yuan, and the indicators have reached the standard.
(2) Production practice shows that under the support of the new low-temperature-resistant collector GE-609, the cationic reverse flotation has good desiliconization effect, strong adaptability to gangue, simple chemical system, no heating, no waterway The advantages of scale and production are smooth, which provides a new process route for refractory iron ore upgrading.
(3) The application of iron concentrates to improve quality and reduce impurities can not only improve the quality of iron concentrates, promote the progress of blast furnace indicators, improve the economic benefits of the system, but also have the role of energy saving and emission reduction, and should be vigorously promoted.