Discussion on Beneficiation Process of Magnetite in Inner Mongolia

Wang Hongmei

(Shandong Gold Ridge iron ore beneficiation plant, Shandong Zibo 255080)

Abstract : The nature of magnetite ore in Inner Mongolia is complex, containing 36.22% of iron and 1.197% of sulfur. The size of magnetite inlay is fine, and the harmful elemental sulfur is not easy to be removed. The ore dressing process of the first floating magnetic is determined. Using reverse flotation desulfurization, and determined by the experiments grinding fineness -0.074mm90%, isoamyl xanthate dosage of 150g / t, 2 # oil usage 60g / t, the slurry pH of 5.5, an amount of copper sulfate, 400g / t of The best beneficiation conditions, verification tests show that the iron concentrate grade can reach 64.81%, the iron recovery rate is 72.82%, and the iron concentrate contains only 0.415% sulfur.
Key words : beneficiation process; magnetite; grinding grain size; floating-magnetic joint process
CLC number : TD951 Document code : B Article ID : 1004-4620 (2004) 05-0051-02

The magnetite mine in Inner Mongolia is a skarn type ore. The main useful mineral is magnetite. The associated minerals are pyrite, chalcopyrite and pyrrhotite. The gangue minerals are mainly quartz , calcite, etc. The magnetite inlays are fine in size, and the harmful impurities are mainly sulfur. The research requires that the iron concentrate grade of iron concentrate should be no less than 64%, the concentrate contains less than 0.5% sulfur, and the recovery value of copper and cobalt should be discussed.
Preparation of a sample ore and laboratory indicators
The ore sample used in the test has a maximum ore particle size of 150 mm. The ore sample is broken to 2mm or less, mixed by the stacking cone method, and the bag is shrunk by the cutting ring method, and 1kg per bag is used for standby. The raw ore test indicators are shown in Table 1. It can be seen from Table 1 that the copper and cobalt grades in the ore are low, and there is no recovery value.

Table 1 Raw mineral test indicators %

SiO ₂

36.22

1.197

0.042

0.0095

16.84

2 Grinding particle size test
Grinding particle size test uses Ï† 240mm Ã— 200mm cone ball mill , grinding concentration of 68%, grinding 1kg each time. The test indicators are shown in Figure 1. Grinding tests show that the ore is hard and difficult to grind.

Figure 1 Relationship between grinding particle size and time [next]

3 Discussion on mineral processing methods
First, the test was carried out using the simplest magnetic separation method. The selected magnetic field strength is 119Ã—103 A/m, and the beneficiation index is shown in Table 2.

Table 2 Single magnetic separation test index %

-0.074mm content	63	68	73	78	88	96
Iron concentrate grade	57.64	58.21	58.47	59.21	61.47	63.55
Concentrate containing sulfur	0.834	0.841	0.844	0.837	0.834	0.835

It can be seen from Table 2 that the single magnetic separation method has a very poor desulfurization effect, and the iron concentrate grade cannot meet the requirements. In order to reduce the sulfur in the iron concentrate to less than 0.5%, the most effective method is to use the reverse flotation method for desulfurization. It was decided to adopt the first floating and magnetic combination process, using 2# oil as the foaming agent , copper sulfate as the activator , the acidity and alkalinity of the pulp and the type of the collector were determined by experiments. The flotation test uses a 3L flotation machine , the flotation process is a coarse sweep, and the rough sweep time is 8 min each. In addition to the regulator, the other three agents were added in a ratio of 2:1 in the roughing and sweeping operations, and the flotation test procedure is shown in Figure 2. The following flotation condition tests use this process.

Figure 2 Beneficiation test process

3.1 Determine the type of collector and the acidity and alkalinity of the pulp
The xanthate is used as a collector, and the slurry is adjusted to be acidic and alkaline with sulfuric acid and lime respectively. The fixed yellow amount is 150g/t, 2 ^# oil is 90g/t, copper sulfate is 600g/t, and the grinding grain size is 90. %, carry out the floating-magnetic selection test, the indicators are shown in Table 3.

Table 3 Different collectors and pH test indicators

project	Ethyl xanthate	Ethyl xanthate	Butyl xanthate	Butyl xanthate	Isoplavone	Isoplavone
pH value	6.0	8.5	6.0	8.5	6.0	8.5
Iron boutique /%	63.18	62.91	64.41	64.25	64.32	64.69
Concentrate sulfur /%	0.65	0.75	0.55	0.72	0.49	0.71

[next]

It can be seen from Table 3 that flotation should be carried out under acidic conditions, that is, sulfuric acid as a regulator and isoplavone as a collector.
3.2 Determine the best mineral processing conditions
The main factors affecting the mineral processing index are: grinding particle size, yellow drug dosage, 2 ^# oil dosage, pulp pH value and copper sulfate dosage.
3.2.1 Grinding particle size test The fixed yellow drug dosage is 120g/t, the 2 ^# oil dosage is 75g/t, the pH value is 6.0, the copper sulfate dosage is 600g/t, and the grinding particle size test index is shown in Table 4.

Table 4 Grinding particle size test indicators %

-0.074mm content	Iron yield	Iron boutique		Iron recovery rate
-0.074mm content	Iron yield	Fe	S	Iron recovery rate
75	43.11	62.51	0.515	74.40
85	42.28	63.54	0.505	74.17
90	41.21	64.55	0.498	73.44
95	40.21	64.52	0.498	71.74

It can be seen from Table 4 that the grinding particle size is selected to be -0.074 mm and the content is 90%.
3.2.2 Isoamyl yellow drug dosage test fixed grinding grain size 90%, 2 ^# oil dosage 75g / t, pH value 6.0, copper sulfate dosage 600g / t, isoamyl yellow drug dosage test indicators see Table 5 .

Table 5 Isoprenyl Yellow Pharmaceutical Test Index %

Yellow dose /gt ^-1	Iron yield	Iron boutique		Iron recovery rate
Yellow dose /gt ^-1	Iron yield	Fe	S	Iron recovery rate
90	41.88	64.05	0.525	74.06
120	41.22	64.40	0.502	73.38
150	41.09	64.45	0.487	73.11
180	40.61	64.44	0.489	72.25

The test results show that the dosage of isoamyl yellow is 150 g/t. [next]
3.2.3 2 ^# oil dosage test fixed grinding grain size 90%, isoamyl yellow drug dosage 150g / t, pH value 6, copper sulfate dosage 600g / t, 2 ^# oil dosage test indicators see Table 6.

Table 6 2 ^#æ²¹é‡è¯•éªŒæŒ‡æ ‡ %

2 ^# æ²¹é‡ /gt ^-1	Iron yield	Iron boutique		Iron recovery rate
2 ^# æ²¹é‡ /gt ^-1	Iron yield	Fe	S	Iron recovery rate
45	42.18	63.88	0.518	74.39
60	41.09	64.51	0.468	73.18
75	40.51	64.51	0.488	72.15
90	40.11	64.52	0.485	71.45

Tests have shown that the optimum amount of 2 ^# oil is 60g/t.
3.2.4 Pulp pH test The fixed grinding grain size is 90%, the isoamyl yellow drug dosage is 150g/t, the 2 ^# oil dosage is 60g/t, the copper sulfate dosage is 600g/t, and the pulp pH value test index is shown in Table 7.

Table 7 Pulp pH test indicators

pH value	Iron yield /%	Iron boutique / %		Iron recovery rate /%
pH value	Iron yield /%	Fe	S	Iron recovery rate /%
6.5	41.88	64.10	0.515	74.12
5.5	40.87	64.59	0.465	72.88
4.5	40.77	64.43	0.475	72.52
3.5	40.89	64.35	0.487	72.65

Tests have shown that the pH of the pulp is most suitable for 5.5.
3.2.5 The amount of copper sulfate used for the test is 90% fixed grain size, 150g/t for isoamyl yellow, 60g/t for 2 ^# oil, 5.5 for pulp, and 8 for copper sulfate. [next]

Table 8 % test index of copper sulfate dosage

Copper sulfate dosage /gt ^-1	Iron yield	Iron boutique		Iron recovery rate
Copper sulfate dosage /gt ^-1	Iron yield	Fe	S	Iron recovery rate
200	41.86	64.11	0.510	74.09
400	40.69	64.78	0.425	72.77
600	41.21	64.56	0.468	73.45
800	40.21	64.55	0.482	71.66

Tests have shown that the optimum amount of copper sulfate is 400g/t.
3.3 Verification test
According to the optimal scheme determined by the experiment, the grinding particle size is 90%, the isoflavone dosage is 150g/t, the 2 ^# oil dosage is 60g/t, the pH value is 5.5, and the copper sulfate dosage is 400g/t. Table 9.
In the verification test, the grade of iron concentrate reached 64.81%, the sulfur content in iron concentrate decreased to 0.415%, and the iron recovery rate was 72.82%.

Table 9 Verification test indicators %

name	Yield	grade		Recovery rate
name	Yield	Fe	S	Fe	S
Raw ore	100	36.22	1.197	100	100
Iron concentrate	40.70	64.81	0.415	72.82	14.11
Tailings	59.30	16.60	1.734	27.18	85.89

4 Conclusion
4.1 Inner Mongolia magnetite ore dressing should adopt a floating-magnetic combined process, first performing reverse flotation desulfurization, and then magnetically selecting the flotation tailings.
4.2 The best beneficiation conditions are grinding particle size -0.074mm90%, isopentyl medicinal amount 150g/t, 2 ^# oil dosage 60g/t, pulp pH value 5.5, copper sulfate dosage 400g/t. Under this condition, the grade of iron concentrate can reach 64.81%, the sulfur content in iron concentrate can be reduced to 0.415%, and the iron recovery rate can reach 72.82%.
4.3 The copper and cobalt grades in Inner Mongolia magnetite are low, and there is no recovery value at present.

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