Experimental study on ore dressing of a low grade phosphate rock

Phosphorus ore is a generic name that can be utilized economically phosphate minerals, is an important chemical raw material. China's phosphate resources are relatively abundant, and the total amount of proven resources is second only to Morocco, ranking second in the world. The main features of phosphorus mineral resources in China are: large reserves, but the distribution is too concentrated; low-grade ore, lean ore and more; and more difficult to beneficiation, beneficiation and less prone; inclined to difficult mining gently inclined thin to medium orebody and more It is suitable for large-scale high-strength mining.

In recent years, with the adjustment of China's mining policy and the sustained and healthy development of the national economy, the demand for various mineral products has continued to grow. The Ministry of Land and Resources has listed the point mines as 20 that cannot meet the needs of national economic development after 2010. One of the minerals.

Of magnesium for a low-grade phosphate rock ore mass laboratory scale continuous flow experiment and test. Previously, most of the magnesia phosphates used phosphoric acid as an inhibitor. Due to the high price of phosphoric acid, the cost of ore dressing was very high. On the other hand, there was no high-performance collector , the ore dressing efficiency was low, and the economic benefit was effective. The ore dressing technology could not be truly converted into productivity. In this test, sulfuric acid was used instead of phosphoric acid, and the new collector TF-66 was used to reduce the cost of ore dressing. At the same time, excellent technical indicators were obtained, which made it possible to convert the beneficiation technology into productivity, which is a major in phosphate ore dressing. breakthrough.

The low-grade magnesia phosphate ore contains P ₂ O ₅ 20.48% and MgO 9.45%. The process test was carried out by using sulfuric acid and TF-66 agent and grinding to a content of 74 μm of 70.4%, and a phosphorus concentrate having a P ₂ O ₅ content of 35.94% and a recovery rate of 88.27% was obtained. Continuous and stable operation of the expansion test 72h, the resulting concentrate containing P ₂ O ₅ 36.15% 90.76% recovery, concentrate MgO content of 0.839%, P ₂ O ₅ tailings content of only 3.90%. The indicators are very good.

First, the nature of the ore

The phosphate rock is a magnesia-phosphorus ore, mainly composed of two types of minerals, apatite and dolomite. It has a cryptocrystalline structure, a mud crystal structure, a fine-microcrystalline structure, a granule structure, and a band structure. Mainly striped strip structure.

Apatite: light brown under the microscope, into a "gelatinous" microscopic crystal. The micro apatite is aggregated in the ore and produced as agglomerates. The agglomerates are formed by chemical coagulation, which are basically ellipsoidal, sub-spherical, spherical, with rounded edges, no prismatic edges, and most of the long diameters are between 0.15 and 0.25 mm, accounting for about 70% of the total aggregates, and the long diameter is 0.25 to 0.3 mm. About 5%, long-term 0.10 ~ 0.15mm accounted for about 25%. There are also a few irregularly shaped agglomerates with large variations in particle size and aspect ratio. In the interior of the apatite mineral agglomerates, a small amount of fine dolomite, chalcedony and other impurities are often mixed.

Dolomite: The mirror is light-colored, colorless and transparent, and it is granular. The monomer grain size is at least 0.02 mm, the maximum is 0.1 mm, and the majority is 0.03 to 0.08 mm. In the phosphate ore, 95% of the dolomite is aggregate, which appears as a cement and a small amount is distributed inside the apatite apatite pellet. About 10% of the dolomite in the phosphate ore is finely distributed in the interior of the apatite pellet and apatite together to form a pellet, and the particle size is mostly 5-10 μm.

Quartz , under the microscope, colorless, bottom protrusion, microcrystalline aggregate, single crystal particle size 0.02 ~ 0.03mm, agglomerated into an irregular shape, distributed in the apatite pellet, a small amount of irregular, vein-like distribution in phosphorus Outside the gray stone pellet. Most of the quartz is closely symbiotic with the apatite pellets. Produced inside the apatite pellet. There are a small amount of fine quartz grain crumbs embedded in the dolomite with a maximum grain size of 0.2 mm.

Calcite : not much content, mostly in its shape. It is mainly distributed in the later cracks in a vein-like and intermittent shape. The particle size is generally 0.05-0.75 mm. A small amount of sporadic distribution between the dolomite particles between the phosphorus aggregates is generally 0.02-0.2 mm.

Other mineral: water mica, pyrite were trace. Under the microscope, the water mica is mostly distributed in the micro-wafer form in the apatite apatite aggregate, the content is less than 1%; the pyrite content is very small, the particle size is generally 2 ~ 5μm, mostly distributed in the dolomite cement, a small amount Within the apatite pellet. The results of multi-element analysis of ore chemistry are shown in Table 1.

Table 1 Results of multi-element analysis of ore chemistry

Second, the beneficiation test

Phosphate ore has many methods of mineral processing, including positive flotation, reverse flotation, scrubbing, and heavy media sorting. There are many studies on the ore dressing of phosphate rock at home and abroad, and the most effective one is flotation. The flotation method includes processes such as positive flotation, reverse flotation, positive-reverse flotation, and double reverse flotation. The positive-reverse flotation process and the reverse flotation process are used more in production practice. When the ore is a siliceous phosphate rock, the positive flotation method is adopted, such as the Jinping Phosphate Mine in Jiangsu; when the ore is a siliceous magnesia phosphate, the positive-reverse flotation method is used, such as the Hubei Wangji Phosphate Mine; The quality or magnesia colloidal phosphate mine adopts reverse flotation method, such as Guizhou Yanfu Phosphorus Mine. Among the collectors used in the reverse flotation and magnesium reduction of magnesia phosphate rock, the new TF-66 agent researched and deployed by our company has good selectivity and collection capacity, and is a by-product of petroleum refining. It has a wide range of sources and is non-toxic. .

(1) Laboratory test

1. Grinding fineness test

The grinding fineness test process is shown in Figure 1. From the test results in Table 2, it can be seen that with the increase of grinding fineness, the P ₂ O ₅ content in the concentrate gradually increases, the recovery rate increases, and the MgO content gradually increases. reduce. When the grinding fineness -74μm accounted for 70.4%, the P ₂ O ₅ content in the concentrate has reached 34.47%, the recovery rate is 84.88%, the MgO content is 1.79%, and the MgO removal rate has reached 90.46%. When the grinding fineness is continued to increase, the P ₂ O ₅ grade and recovery rate in the concentrate are not significantly changed, but the grinding cost is significantly increased. Therefore, the grinding fineness - 74 μm was determined to be 70.4%.

2, sulfuric acid dosage test

Table 2 Grinding fineness test results

The test results of sulfuric acid dosage are shown in Table 3. It can be seen from Table 3 that with the increase of the amount of sulfuric acid, the content of P ₂ O _{5 in the} concentrate gradually increases, the content of MgO decreases gradually, and the recovery rate of P ₂ O ₅ increases rapidly. Considering comprehensively, the amount of sulphuric acid is 12kg/t. At this time, the content of P ₂ O _{5 in the} concentrate is 32.56%, the recovery rate is 90.95%, and the MgO content is 2.76%.

Table 3 Sulfuric acid dosage test results

3, TF-66 dosage test

The amount of fixed sulfuric acid used in the test was 12 kg/t, and the dose test of TF-66 was carried out. From the test results in Table 4, it is known that with the increase of the amount of collector TF-66, the concentrate yield gradually decreases, the P ₂ O ₅ content in the concentrate gradually increases, the MgO content decreases, and the exclusion rate of MgO in the tailings increases. When the amount of collector TF-66 is 1000g/t, the recovery of P ₂ O _{5 in the} concentrate is 32.66%, the recovery rate has reached 91.12%, and the MgO elimination rate is 83.08%. Therefore, it was determined that the amount of the collector TF-66 was 1000 g/t.

Table 4 TF-66 dosage test results

4, open circuit test

According to the flow and test conditions of Figure 2, the test results in Table 5 show that after a selection, the phosphate concentrate with a grade of 36.69% and a recovery rate of 86.46% can be obtained. The MgO content in the concentrate is only 0.82%. The flotation mine has a good sorting effect, and after re-election, it can also obtain a concentrate with a grade of 30.69%. The P ₂ O ₅ content in the tailings is 4.26%, and the loss rate is only 8.94%.

Table 5 Open circuit test results

5, closed circuit test

The closed circuit test was carried out according to the flow and conditions of Fig. 3. The test results are shown in Table 6.

Table 6 Closed circuit test results

(2) Expanding continuous trials

The task of expanding the continuous test is to verify and determine the pharmaceutical system and beneficiation process developed under laboratory conditions. In most cases, the working system of intermittently fed laboratory equipment is different from the working system of continuously operating equipment, thereby reducing the reproducibility of the beneficiation process indicators. Under laboratory conditions, the grinding operation is without control grading, and the closed-circuit process with medium-mine return is purely a simulation of continuous test. In order to verify the reliability of the process system and process structure of the process test, an extended test of continuous operation for 72 hours was carried out. The expanded continuous test system is shown in Figure 4. The process conditions and test results are shown in Tables 7 and 8. It can be seen from the data in Table 8 that the index of phosphorus concentrate obtained by expanding the continuous test is better than the process test, which fully verifies that the process system determined by the process test has high reliability and high index.

1-Original mine bin; 2-90×110 pendulum type feeder; 3-φ420×450 lattice type continuous ball mill ;

4-φ200×1650 spiral classifier; 5-6XDT8L slurry mixing bucket; 6-FX mechanical stirring continuous flotation machine

Table 7 Expanding continuous test process conditions

Table 8 Expanding the results of continuous tests

Third, the conclusion

(1) The ore is a low-grade magnesia-phosphorus ore with P ₂ O ₅ 20.48% and MgO 99.45%, mainly composed of two kinds of minerals, apatite and dolomite. It has a cryptocrystalline structure, a mud crystal structure, a fine-microcrystalline structure, a granule structure, and a band structure. Mainly striped strip structure.

(2) When the ore fineness -74μm accounted for 70.4%, the new collector TF-66 was used, and the yield was 50.28% and the grade was 35.94% after one rough selection and two selected closed-circuit processes. The recovery rate is 88.27% of the phosphate concentrate, and the MgO content in the concentrate is 0.89%.

(3) On the basis of the process test, the continuous continuous test was carried out. The test was continuously and stably operated for 72 hours. The P ₂ O ₅ grade in the phosphate concentrate product was 36.15%, the recovery rate was 90.76%, and the MgO content in the concentrate was 0.84%. . The process system and process structure determined by the process test are fully verified to have high reliability and good reproducibility.

(4) The new collector TF-66 is suitable for low-grade magnesia phosphate rock. The mineral processing technical index is very ideal and reproducible, which provides a favorable basis for the development and utilization of the phosphate rock.