A beneficiation plant eight series is a typical continuous grinding - weak magnetic - reverse flotation process magnetic iron ore processing production line, but because of its complicated nature of the ore, and there is a mixed phenomenon magnetite ore and oxide ore, so The recovery rate of iron in this series has been relatively low since it was put into production. In the current situation of increasingly tight resources, it is especially important to make full use of resources and increase the recovery rate of iron. To this end, for the specific production indicators of mineral processing, a pilot study to improve the iron recovery rate was carried out.

After years of production and operation, the grinding process and weak magnetic separation process and equipment configuration are reasonable. Therefore, the experimental sample is selected as weak magnetic separation concentrate and weak magnetic separation tailings. Sorting of weak magnetic separation tailings. The purpose of the research is to find out the reasons for the low iron recovery rate through experimental research, and to find ways and ways to improve the recovery rate of magnetic series iron.

First, the experimental mineral sample

(1) Sampling

The experimental ore samples were taken from eight series of ore dressing plants. The ore samples were weak magnetic selective concentrate and weak magnetic roughing tailings. Samples were taken continuously for one week and sampled 6 times a day. At the same time, the series of processing raw ore is also sampled and analyzed and analyzed. The average index of the experimental ore sample taken is: original ore iron grade TFe32.47%, TFeO 11.13% ore average oxidation degree 2.92%; weak magnetic concentrate iron grade TFe61.20%, theoretical yield 37.41%, iron recovery rate 70.51% The weak magnetic rough-choice tailings iron grade is 15.30%, the theoretical yield is 62.59%, and the iron loss rate is 29.49%. The sample taken from the experiment has a certain representativeness from the sampling time, the sampling point, the weight of the sample taken and the index.

(II) Analysis of the nature of the ore sample

1. Material composition and analysis of mineral samples

The multi-element analysis and phase analysis results of the test ore samples are shown in Tables 1 and 2.

Table 1 Multi-element analysis results of test ore samples







SiO 2

Weak magnetic concentrate







Weak magnetic tailings








K 2 O

Na 2 O



Al 2 O 3

Burning down

Weak magnetic concentrate







Weak magnetic tailings







Table 2 Iron phase analysis results of test ore samples

Mineral sample




Iron phase

Iron in magnetite

Iron in hematite

Iron in silicate

Iron in sulfide ore

Weak magnetic







Occupancy rate





Weak magnetic







Occupancy rate





The analysis results show that after the weak magnetic separation of the ore, the recovery rate of magnetite is high, indicating that the on-site magnetic separation process has a good effect on the selection of magnetite. However, the recovery of oxidized ore is very low, and most of it is lost in the tailings. Therefore, to improve the recovery rate of the magnetic ore series, it is mainly to recover the oxidized ore lost in the tailings.

2. Monomer dissociation and particle size analysis of mineral samples

The results of the monomer dissociation analysis of the test ore samples are shown in Table 3, and the particle size analysis results are shown in Table 4.

Table 3 Test results of iron mineral monomer dissociation in test ore samples

Test ore sample

Iron mineral


Fu Liansheng (%)

Poor population (%)

Iron and silicate minerals

Iron and fluorite

Iron and other minerals

Iron and silicate minerals

Iron and fluorite

Iron and other minerals

Weak magnetic concentrate








Weak magnetic tailings








Table 4 Results of particle size analysis of test ore samples

Particle size (mm)








Weak magnetic feeding








Weak magnetic concentrate








Weak magnetic tailings








The composition of the test ore and the dissociation analysis of the monomer indicate that the iron minerals in the weak magnetic tailings have low monomer dissociation and recover iron minerals from the weak magnetic tailings. No matter what method is adopted, it is necessary to obtain a higher iron grade. Iron concentrates, the iron recovery rate is not too high.

The results of particle size analysis show that the weak magnetic tailings have high content of fine-grained minerals, and the iron occupation rate is also high. Therefore, in order to recover iron minerals from weak magnetic tailings, the effective recovery of fine-grained iron minerals must first be considered.

Second, the selection test and its results

(1) Test process

According to the nature of the ore, the experimental scheme used in this study is: direct de-floating-positive flotation test on the weak magnetic tailings of the weak magnetic separation of the concentrator, and exploring ways to improve the series recovery rate; The weak magnetic concentrate is tested on the site by a coarse and two fine reverse flotation process.

The flotation process of weak magnetic tailings is a reverse floating-positive flotation process. Reverse flotation is a combination of Na 2 CO 3 -water glass-paraffin soap combination; positive flotation is a rough selection twice, using alum-fluorosilicate-paraffin soap combination. The test procedure and equipment are shown in Figure 1.

(2) Test results and analysis

1. Results of reverse flotation test of weak magnetic concentrate

In the case that the ore grade is 32.71% and the weak magnetic concentrate grade is 61.83% and the yield is 37.41%, the weak magnetic concentrate can obtain the anti-float concentrate grade of 64.48% after a coarse and two fine reverse flotation. The rate was 34.66%.

2. Test of conditional coarse selection of weak magnetic tailings

The test water is clean water. According to the previous research, and through the exploration test, the amount of crude alum used is 5kg/t, and the amount of sodium fluorosilicate is 1.77kg/t. Under these conditions, the conditions of different dosages of collectors are determined. test. The test results are shown in Figures 2, 3 and 4. It was confirmed from the test results that the amount of the collector was 0.80 kg/t.

3, weak magnetic tailings positive floating selection conditions test

Through the exploratory test, the dosage of the positive float test was determined as: 1.Okg/t for a fine inhibitor and 0.lkg/t for a collector. The test was carried out with clean water, and the result was a sorting index of an iron concentrate operating yield of 10.94%, an iron grade of 50.60%, and an operation recovery rate of 36.50%.

4, weak magnetic tailings anti-floating - positive floating back water test

On the basis of the clean water test, taking into account the site feasibility of the test plan, an open circuit test was carried out with on-site backwater. Tests have shown that the amount of pesticide used in the backwater test is somewhat higher than that of clean water. The specific dosage of the agent is shown in Table 5. The open circuit test results are: the selection index of positive floating concentrate grade 53.10%, operation yield 11.04%, and operation recovery rate 38.71%. The result of the selection is better than the clear water.

Table 5 Anti-floating-positive flotation backwater test agent dosage (kg/t)

Sorting operation

Pharmacy and dosage


Sodium carbonate 1.5

Water glass 2.0

Paraffin wax 0.4

Positive floating selection

Alum 5.0

Sodium fluorosilicate 1.75

Paraffin soap 1.2

Positive float


Sodium fluorosilicate 1.00

Paraffin soap 0.40

Positive float



Paraffin soap 0.30

5, weak magnetic tailings anti-floating - positive floating backwater closed circuit test

The dosage of the return water closed circuit test was slightly adjusted based on the condition test. After the closed-circuit test of the weak magnetic tailings by the reverse float-positive flotation process, the results of the selection of the positive floating iron concentrate grade of 55.06%, the operating yield of 11.20%, and the operating recovery rate of 40.73% are obtained, and the test results reach the expected index. .

The weak magnetic concentrate is subjected to reverse flotation and weak magnetic tailings after the reverse float-positive flotation process, and the final integrated iron concentrate can be obtained. The yield is 41.69%, the iron grade is 62.96%, and the iron recovery rate is 80.13%. The index of impurity fluorine 0.53%. It is more than 10 percentage points higher than the actual recovery rate of the current plant.

Third, product results analysis

The phase analysis and particle size composition analysis of the ore concentrate concentrate and tailings products of the weak magnetic tailings anti-floating-positive flotation process were carried out. The results show that: 1. In the ore-floating iron concentrate, the main minerals are Hematite has a market share of 91.90%; gangue minerals are mainly amphibole and smectite, accounting for 48.95% of the gangue mine brutality. After the anti-floating-positive flotation of the weak magnetic tailings, the recovery rate of non-magnetic iron mineral iron is 45.04%, and the throwing rate of iron-containing silicate mineral iron is 88.37%, indicating the choice of the process and its combination of chemicals. It is very effective for recovering iron from weak magnetic tailings. 2. According to the measurement results of the dissociation degree of the monomer, the recovery of iron minerals from the weak magnetic tailings requires a large yield to obtain a higher oral iron concentrate. Otherwise, the iron concentrate The taste will not be too high. 3. After the weak magnetic tailings are reversed-positive, the amount of 20μm thrown by reverse flotation is 69.02%, and the loss rate of the graded iron is 50.84%. The recovery of fine-grained iron minerals is still an important part of improving the recovery rate of iron minerals.

Fourth, the conclusion

It can be seen from the test results that the direct anti-floating-positive flotation process of weak magnetic tailings is superior to the weak magnetic field that has been performed from the recovery of fine-grained iron minerals or from the recovery of non-magnetic iron minerals. The tailings are re-floated after strong magnetic separation - the result of the process selection. By not changing the production process of the existing mine magnetic series, by increasing the flotation operation, the goal of increasing the iron recovery rate can be achieved, and the process flow is relatively simple. The results of this study provide an important reference for the concentrator to increase the recovery rate of the magnetic ore series in the future.


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