Experimental report on magnetic separation of Zhangjiajie iron ore in Hunan

1 Introduction

With the continuous exploitation and utilization of mineral resources, it is becoming increasingly scarce, and the grade of ore is also decreasing. Not only a large amount of ore needs to be processed by mineral processing, but also more and more ore is difficult to be selected in the ore. In order to explore the nature of Hunan Zhangjiajie iron ore samples provided by the Chongqing Iron and Steel Group Mining Co., Ltd., to provide a reference for its investment in actual production, heavy Steel Group Mining Co., Ltd. Qijiang iron ore complete roasting tests in the laboratory.

2 Test purposes and methods

Conventional roasting methods, and strive to get a higher grade iron ore concentrate, and higher metal recoveries. Through laboratory tests, the relevant parameters such as grinding fineness and magnetic field strength are determined. Explore the nature of Zhangjiajie Iron Mine in Hunan Province and provide reference for actual production in the future.

3 Test content and process

3.1 Preparation of mineral samples

All the ore samples were coarsely crushed in an XPC 150×100 jaw crusher , and then crushed into 0 to 4 mm grade mineral samples by a PC180×150 hammer crusher. The main sample was obtained by dividing the cone cone by a square method, and it was placed in a 101A-4 type electric blast constant temperature drying oven for drying. After the main sample is taken, the remaining sample is taken as a sample and retained. Take 2g of ore sample from the dried main sample and use the -1 type GJ series sealed type test sample pulverizer to prepare the test sample.

The raw ore sample preparation process is shown in Figure 3-1.

Figure 3-1 Flow chart of raw ore sample preparation

3.2 Raw mineral chemical composition

The chemical analysis results of the ore are shown in Table 3-1.

Raw ore chemical analysis Table 3-1

name

Analysis Project(%)

TFe

SiO 2

S

P

Loss

Raw ore

48.30

9.60

0.18

0.715

5.11

3.3 Roasting test

3.3.1 Roasting test equipment

The roasting equipment used in the test is a 4-13 box type resistance furnace manufactured by Shanghai Luda Experimental Instrument Co., Ltd. The main technical parameters are as follows:

(1) Heating chamber size: 250 × 150 × 100mm

(2) Rated power: 4KW

(3) Rated voltage: 220V

(4) Temperature: 1300 ° C

(5) Temperature controller: KSY4-13

3.3.2 Roasting test atmosphere, temperature and time

Since the ore sample is mainly hematite, reference is made to the results of the ore dressing test of Chongqing Iron and Steel Group Mineral Co., Ltd., and the test roasting atmosphere is determined to be a reducing atmosphere (sealing, adding 10% of 0-2 mm coal according to the weight of the sample) Powder), the test roasting temperature is about 900 ° C, and the roasting time is 90 min. The quality index of pulverized coal used for roasting is shown in Table 3-2.

Pulverized coal quality indicators Table 3-2

name

Analysis Project(%)

Aad

Vad

FCad

St,ad

Qnet,ad

Pulverized coal

13.10

9.54

77.36

0.62

7065.84

3.3.3 Roasting test process

Weigh 50g0~4mm ore from the main sample and weigh 5g0~2mm of prepared coal powder, mix it thoroughly, and put it into a ceramic pot. According to the same procedure, a total of 8 well-prepared cockroaches are prepared and the lid is covered. When the temperature in the furnace of the resistance furnace reaches 900 °C, it is placed in the furnace. After heating for 90 minutes, the crucible is quickly taken out and immediately placed in a water basin filled with water for water sealing, and cooled to room temperature. The crucible is taken out and the basin is allowed to stand. After the clarification of the roasting ore in the basin, it is filtered. Finally, the roasted ore sample is dried. Take 2g of ore sample from the dried roasting ore sample and grind it into a sample with a type-1 GJ series sealed type test sample pulverizer.

The firing test procedure is shown in Figure 3-2.

Figure 3-2 Roasting test flow chart

3.4 Grinding magnetic separation test

3.4.1 Grinding magnetic separation equipment

Grinding: Φ140×190 rod mill

Magnetic separation: XCGS74-Φ50 type magnetic tube

3.4.2 Grinding magnetic separation test

(1) Grinding fineness test

Accurately weigh 200 g of dried roasting ore with a plate balance, put it into a rod mill, open the rod mill, and control the grinding time with a stopwatch. Then, the polished ore sample is taken out, and 50 g of the balance is accurately weighed, poured into a -200 mesh sieve, and sieved for 20 minutes with a XSB-200 top-hitting standard sieve shaker, and the sieve is poured out of the sieve. , weighed, by weight of the sieve, calculate the weight percentage of -200 mesh particle size minerals.

When the test grinding time is 20 min, the particle size is -200 mesh 91.00%.

(2) Magnetic field strength test

Three ore samples of the above particle size were weighed in a beaker with a plate balance, and 20 g was placed in each beaker. The magnetic field strength is set to 800 GS (control current intensity is 0.80 A), 1200 GS (control current intensity is 1.20 A), 1600 GS (control current intensity is 1.60 A), and the above three magnetic field strengths are performed on the XCGS74-Φ50 type magnetic separation tube. The magnetic sample test of the ore sample clarifies, filters, dries, weighs and prepares the obtained concentrate and tailings respectively.

(3) Grinding magnetic separation process and test indicators

The grinding magnetic separation test process is shown in Figure 3-3.

Figure 3-3 Flow chart of grinding magnetic separation test

The grinding magnetic separation test indicators are shown in Table 3-3.

Grinding magnetic separation test indicators Table 3-3

Item number

Calcination temperature (°C)

Calcination time (min)

Magnetic field strength (GS)

Grinding fineness (-200 mesh%)

Roasted ore (TFe%)

Concentrate (TFe%)

Tailings (TFe%)

Concentrate yield (%)

Metal recovery rate (%)

1

900

90

800

91.00

47.30

57.23

32.84

58.64

70.95

1200

91.00

47.30

56.94

24.29

70.71

85.12

1600

91.00

47.30

56.64

21.39

73.76

88.32

It can be known from Table 3-3 that as the magnetic field strength increases, the concentrate grade decreases, the tailings grade decreases, the concentrate yield increases, and the metal recovery rate increases.

3.4.3 Product chemical composition

The chemical composition analysis results of the products obtained by roasting magnetic separation are shown in Table 3-4.

Chemical analysis of roasting magnetic separation products Table 3-4

Calcination temperature (°C)

Calcination time (min)

name

Analysis Project(%)

TFe

FeO

SiO 2

S

P

Loss

900

90

Roasting ore

47.06

18.47

-

-

-

7.20

Concentrate

56.64

-

7.75

0.10

0.593

-

Tailings

21.39

-

-

-

-

-

4 Test conclusion

It can be known from the test that 10% of 0~2mm pulverized coal is added according to the weight of the original ore sample. When the calcination temperature is 900°C and the calcination time is 90min, the grade of roasting iron ore is about 47%, and the residual burning loss is about 7%. very high. In the magnetic separation test, as the magnetic field strength increases, the concentrate grade decreases, the tailings grade decreases, the concentrate yield increases, and the metal recovery rate increases.

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