Method for producing ground phosphate rock pellets by using yellow phosphate ore beneficiation pulp

Abstract

The invention relates to the technical field of ground phosphate rock, and particularly discloses a method for producing ground phosphate rock pellets by using yellow phosphate ore beneficiation pulp. Comprising six steps of ore pulp thickening, filter pressing, mineral powder drying, proportioning and mixing, ball pressing and ground phosphate rock pellet drying, and a natural plant-based polymeric flocculant added in the earlier stage is matched with high temperature in the mineral powder drying process, and an organic binder with hydroxyl and phosphoric acid cooperate with each other; the technical problems that the grade of the ground phosphate rock pellets is reduced, the quality and yield of produced yellow phosphorus are reduced, the production cost is increased and the production cost of the yellow phosphorus is increased due to the fact that a large amount of adhesives are input in the production of the ground phosphate rock pellets in the prior art due to the strength requirement are solved.

Description

Technical Field

[0001] The invention relates to the technical field of phosphate rock powder, in particular to a method for producing phosphate rock powder pellets by utilizing yellow phosphate ore dressing slurry. Background Art

[0002] Yellow phosphorus, also known as white phosphorus, is an allotrope of phosphorus and an important chemical raw material. It can be used in the manufacture of phosphorus compounds such as thermal phosphoric acid, phosphorus trichloride, phosphorus oxychloride, and phosphorus pentasulfide in industry, and in the production of various phosphates in agriculture. It has a wide range of uses. The main raw material for yellow phosphorus production in my country is phosphate rock, so when producing yellow phosphorus, it is necessary to beneficiate phosphate rock and use the selected phosphate concentrate to prepare yellow phosphorus or phosphoric acid.

[0003] The industrially large-scale phosphate beneficiation methods include flotation and scrubbing. Both methods will produce tailings. On the whole, for every ton of phosphate concentrate produced, 0.44 tons of tailings will be produced. The tailings produced by the flotation method usually exist in the form of slurry. The direct discharge of this part of the tailings slurry will pollute the water body. Therefore, in the traditional technology, a tailings pond will be built to collect the tailings slurry, and then the water in the tailings slurry will be removed by the dehydration and dry discharge process to form tailings mud powder for discharge; but the discharged tailings storage requires a large amount of land, and it is also easy to cause environmental pollution, soil erosion, and vegetation destruction. In addition, a large amount of stored tailings is easy to flow and collapse, and it is very easy to collapse and landslide in the rainy season, causing serious safety hazards. Not only that, the tailings slurry still contains a large amount of phosphate ore powder, and its P2O5 content is about 22%, which belongs to medium and low-grade phosphate ore. With the rapid development of phosphorus chemical industry and the disorderly mining and serious waste of phosphate rock, the reserves of high-grade phosphate rock in my country are decreasing sharply. Discharging this part of low-grade tailings directly as solid waste not only increases the cost of environmental protection treatment, but also greatly wastes resources. If it is recycled, the tailings powder is small and low in grade, so it cannot be directly put into the electric furnace to produce yellow phosphorus by high-temperature reaction.

[0004] In this regard, the prior art has developed a method of preparing phosphate rock powder pellets from tailings powder, and then using the phosphate rock powder pellets to produce yellow phosphorus, and recovering the phosphorus resources in this part of the tailings. For example, the patent with application number: CN200910094231.2 discloses a method for preparing yellow phosphorus from medium and low-grade phosphate ore, in which medium and low-grade phosphate ore is prepared into pellets for the production of yellow phosphorus. Another example is the patent document with application number: CN202211688146.0 discloses a method for producing yellow phosphorus from cyclone tailings pellets, which also prepares tailings into tailings pellets and then uses them to produce yellow phosphorus. This method of first preparing phosphate rock pellets and then using them to prepare yellow phosphorus allows the tailings powder to form a structure similar to phosphate ore and can be recovered.

[0005] However, the improvement of this process also leads to the production quality and cost of phosphate rock powder pellets, which directly affects the production quality and cost of yellow phosphorus. In the prior art, for the production of phosphate rock powder pellets, phosphate rock and adhesive are usually mixed to prepare pellets, and then sintered to form them. For example, Chinese patent CN107032311A discloses a yellow phosphate ore powder pelletizing method, which uses a mixture of water glass, clay, pulp, etc. as an adhesive, and its dosage is 8% to 10% of the mass of the ore powder. Compared with other domestic adhesives, this method solves the problems of strength and other issues, but it has the same defects as other methods for preparing phosphate rock powder pellets on the market, either the amount of adhesive is relatively large, or the strength of the phosphate rock powder pellets is insufficient. This method uses a large amount of adhesive, which leads to a decrease in the taste of yellow phosphorus entering the furnace, thereby increasing the energy consumption of yellow phosphorus. The input of adhesives leads to an increase in the production cost of phosphate rock powder pellets, which in turn leads to an increase in the cost of yellow phosphorus production. Therefore, seeking a low-cost method for preparing phosphate rock powder pellets is a hot topic in the industry. Summary of the invention

[0006] The object of the present invention is to provide a method for producing phosphate rock powder pellets using yellow phosphate ore dressing slurry, so as to solve the technical problem that in the prior art mentioned above, due to the strength requirement of phosphate rock powder pellet production, a large amount of adhesive is added, resulting in a decrease in the grade of phosphate rock powder pellets, a decrease in the quality and output of yellow phosphorus production, an increase in production cost, and thus an increase in the production cost of yellow phosphorus.

[0007] In order to solve the above problems, the technical solution adopted by the present invention is as follows: A method for producing phosphate rock powder pellets using yellow phosphate ore dressing slurry comprises the following steps:

[0008] S1: Slurry thickening: The ore pulp from the ore dressing is transported to the thickener for solid-liquid separation, and flocculants are added to flocculate the mineral powder in the ore pulp to obtain high-concentration ore pulp;

[0009] S2: Filtration: The high-concentration slurry is transported to the filter press for filtration to obtain a ore powder filter cake;

[0010] S3: Mineral powder drying: the mineral powder filter cake is passed into a dryer for drying at a drying temperature of 1000-1200°C to obtain dried mineral powder;

[0011] S4: Proportional mixing: Mix the dried mineral powder and silica powder, the mass of the silica powder accounts for 8-12% of the dried mineral powder, and after mixing evenly, add 1% of the weight of the silica powder and the mineral powder mixture and 2% of phosphoric acid and continue mixing, and mix for 5 minutes to obtain a mixed mineral material;

[0012] S5: Ball pressing: The mixed ore is fed into a ball press to be pressed into wet phosphate rock powder pellets;

[0013] S6: drying phosphate rock pellets: drying the wet phosphate rock pellets in an environment of 80-550°C to obtain phosphate rock pellets;

[0014] The flocculant in S1 is a natural plant-based polymer flocculant, and the adhesive is an organic adhesive with hydroxyl groups.

[0015] The beneficial effects of this embodiment are:

[0016] 1. The present application starts with the sedimentation of the slurry, and selects a natural plant-based polymer flocculant. When the ore powder is dried, it is carbonized at high temperature, and an organic binder is used when adding the adhesive. Both do not contain silicon dioxide and other inorganic mineral components, so the phosphorus content of the pellets will not be reduced due to the addition of flocculants and adhesives, and the taste of the formed pellets will not be reduced. Therefore, the quality and output of the yellow phosphorus production can be improved, and the production cost can be reduced. When the natural plant-based polymer flocculant and the organic binder are put into the furnace for production, the organic binder is carbonized and plays a reducing role together with the carbon powder formed by the natural plant-based polymer. The carbon powder is directly burned after reduction to form carbon dioxide gas, so the porosity of the pellets is increased, and the temperature of the electric furnace can more easily reach the sphere, so that the reaction is more sufficient, so that the yellow phosphorus production is high.

[0017] 2. The tailings slurry concentration after phosphate ore dressing is 14.2% and the density is 1.1g / mL. In order to facilitate the subsequent filter pressing, its concentration needs to be increased. To this end, it is introduced into a thickener for thickening operation to increase the concentration of the slurry. However, in actual use, it is found that the slurry is not easy to settle and the concentration of the bottom flow slurry of the thickener is low (about 43%-45%). For this reason, this application uses particle size analysis, and the results are as follows Figure 1 As shown, the particle size of phosphate rock powder in the tailings slurry is less than 10 microns, accounting for 60%, and less than 45 microns, accounting for 98%. The results show that the tailings slurry of phosphate rock has fine particles. Because the particles are too fine, the bottom flow concentration of the thickener is low. In this application, flocculants are added during filtration. The flocculants capture the mineral powder with too fine particles to form large particles. The precipitation of mineral powder in the thickener is faster, and the concentration of the bottom flow slurry of the thickener is increased to about 60%, which improves the efficiency and quality of thickening. The concentration in the thickener is increased, which can reduce the working pressure of the filter press. For example, if 50 tons of 60% concentration slurry can only be thickened to 40%, its mass will become 75 tons, which greatly increases the workload and energy consumption of the filter press section. After the application uses flocculants for thickening, its mass is greatly reduced, the workload and energy consumption of the filter press end are reduced, the production efficiency of its mineral powder pellets is improved, and the cost of a single pellet is reduced. Furthermore, the flocculant in the present application forms porous floccules when the mineral powder slurry settles, so that when it is filtered, the floccules form void channels for water to quickly escape from the mineral slurry, thereby improving its filtering state, and thus its filtering efficiency is higher.

[0018] 3. The flocculant added to the slurry during the thickening of the present application is a plant-based flocculant. Therefore, the mineral powder formed after flocculation contains a large amount of plant-based molecules. When dried in S3, since the drying temperature is above 1000°C, the plant macromolecules in the plant base will be carbonized to form carbon powder that is evenly mixed with the mineral powder. This part of carbon powder formed by carbonization of the flocculant can increase the reducibility of the pellets, making it easier to be reduced during the smelting process, thereby improving the extraction efficiency of phosphorus and the quality of the smelting products.

[0019] 4. Since the adhesive in the present application contains hydroxyl groups, which react with phosphoric acid to form lipid groups, adding phosphoric acid can form double superimposed strength with the adhesive, greatly improving the wet ball strength of the pellets, preventing them from breaking when entering the dryer for pellet drying, and increasing the pellet formation rate.

[0020] 5. Mineral powder pellets In the process of yellow phosphorus production in yellow phosphorus electric furnace, the resistance of the charge is increased, so the electrode can be deeply inserted, the reaction zone of the electric furnace crucible can be expanded, the heat can be concentrated, and the thermal efficiency in the height direction of the electric furnace can be improved, thereby reducing the specific power consumption and specific coke consumption. At the same time, increasing the resistance of the charge will reduce the current, thereby improving the electrode efficiency and power factor. Therefore, the specific resistance of the charge is closely related to the single specific power consumption and output in smelting. The adhesive used in this application is a polymer compound with a large specific resistance. At the same time, many active groups in its long-chain molecules can react with ions on the surface of mineral particles to form complexes, generate chemical bonds and hydrogen bonds to enhance the non-electrical properties of the charge, and significantly increase the specific resistance. Therefore, when it is put into the furnace for yellow phosphorus production, its energy consumption is lower.

[0021] Furthermore, the natural plant-based polymer flocculant is a modified guar gum-based sedimentation agent.

[0022] Furthermore, the natural plant-based polymer flocculant is a lignin derivative flocculant.

[0023] Furthermore, the adhesive is Peridot.

[0024] Furthermore, the adhesive is QTHL-03 pellet adhesive.

[0025] Furthermore, the S4 mixture contains 1% of adhesive and 2% of phosphoric acid. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 is a flow chart of an embodiment of the present invention,

[0027] Figure 2 This is a particle size distribution diagram of the slurry according to an embodiment of the present invention. DETAILED DESCRIPTION

[0028] The following is further described in detail through specific implementation methods:

[0029] The reference numerals in the drawings of the specification include:

[0030] Implementation example Figures 1-2 As shown:

[0031] Example 1

[0032] S1: Slurry thickening: The rotor tailings slurry after phosphate ore flotation is transported to the thickener for solid-liquid separation, and flocculants are added to flocculate the ore powder in the slurry to obtain high-concentration slurry;

[0033] The tailings slurry concentration after phosphate ore dressing is 14.2% and the density is 1.1g / mL. In order to reduce the volume of tailings slurry during the later filter pressing, its concentration needs to be increased. To this end, it is introduced into a thickener for thickening operation to increase the concentration of the slurry. However, in actual use, it is found that the slurry is not easy to settle and the underflow concentration of the thickener is low (about 43%-45%). For this reason, the present application uses particle size analysis, and the results are as follows Figure 2 As shown, the particle size of phosphate rock powder in the tailings slurry is below 10 microns, accounting for 60%, and below 45 microns, accounting for 98%. The results show that the tailings slurry of phosphate rock has fine particles. Because the particles are too fine, the bottom flow concentration of the thickener is low.

[0034] In this regard, in this embodiment, 1% of natural plant-based polymer flocculants are added to increase the sedimentation effect of the thickener, more efficiently precipitate phosphate rock powder, increase the underflow concentration of the thickener, reduce the sedimentation time, reduce the workload for subsequent filter pressing, and do not introduce new inorganic and other mineral components, and do not reduce the taste of the later pellets. To improve the efficiency of the process, the precipitant used in this embodiment is a modified guar gum-based sedimentation agent (Mining and Metallurgical Technology Group-BGRIMM Agent).

[0035] There are two types of thickeners on the market, one with a rake and the other without a rake. The effects of the rakes are different for different materials to be thickened. Some materials are easily disturbed by the rakes and are not easy to settle, affecting their ultimate concentration. In this regard, experiments were conducted on phosphate ore slurry with added flocculants to explore the effect of the rakes on it.

[0036] In order to explore the ultimate concentration of phosphate ore slurry, sedimentation concentration tests with and without rakes were carried out.

[0037] Experimental equipment

[0038] The dynamic flocculation sedimentation test uses a 2L flocculation sedimentation special equipment with a driven rake frame. Other auxiliary equipment includes a flocculant addition mixer, a beaker, an analytical balance, an electronic balance, a drying oven, etc. The main equipment technical indicators are: (1) Drive rake frame: 5r / min (T = 2Nm, D1 = 6.0cm, D2 = 3.5cm) (2) Graduated cylinder: 2000mL

[0039] Test methods and test steps

[0040] A flocculant solution with a concentration of 0.1% was prepared, and a tailings slurry solution with a concentration of 12% was configured, and the tailings slurry configuration volume was 2000ml. The flocculant solution was then added to the evenly stirred tailings slurry by a professional slurry mixer to ensure sufficient mixing with the slurry. After the test started, the driving rake in the sedimentation device was turned on, and the settlement height of the tailings at the clarified liquid level was observed at different times. After the slurry was left to stand for a period of time, the stable sand surface height was read. The flocculant selected was: Mining and Metallurgical Group Plant Gum; flocculant addition amount: 40g / t; slurry volume: 2000m3. A total of 3 groups of dynamic flocculation and sedimentation tests were carried out, 2 of which were with rakes and 1 without rakes.

[0041] The test results are shown in the following table:

[0042] Serial number Whether to bring a rake Settling time concentration / % 1 no 4h 35 2 bring 0.5h 54 3 bring 1.5h 60 4 bring 4h 61

[0043] Table 1 Sedimentation test results

[0044] It can be seen from Table 1 that the phosphate tailings can be concentrated to about 60% by stirring with a rake, which is much better than the concentration effect without a rake. Therefore, the BGRIMM-HPT paste deep cone thickener with a rake is selected in this embodiment.

[0045] S2: Filtration: The high-concentration slurry is transported to the filter press for filtration to obtain a ore powder filter cake;

[0046] The filter press section is mainly used to further reduce the moisture content in the tailings slurry, so as to reduce the drying pressure for the subsequent drying of the tailings slurry. Therefore, the lower the moisture content after filter pressing, the lower the energy consumption of drying and the lower the cost.

[0047] In this embodiment, a 630-type single-chamber feed light and dark dual-purpose filter press is used to press the tail slurry, and the process controls the pressing pressure to 20kg / cm2, the pressing time to 10min, the blowing pressure to 10kg / cm2, and the blowing time to 1min for pressing.

[0048] S3: Mineral powder drying: the mineral powder filter cake is passed into a dryer for drying to obtain dried mineral powder;

[0049] The pressed mineral powder filter cake is transported to a horizontal dryer for drying. During drying, the temperature needs to be controlled at 1100°C to ensure that the filter powder is dried at high temperature and that the plant-based flocculant is carbonized.

[0050] S4: Proportional mixing: Mix the dried mineral powder with silica powder, the mass of the silica powder accounting for 8-12% of the dried mineral powder, and after mixing evenly, add adhesive and phosphoric acid to continue mixing and maturing to obtain a mixed mineral material;

[0051] Since flocculants are used in the production of mineral powder, the mineral powder after production has uneven particles and agglomerates, and it is necessary to crush the materials to make them relatively uniform. Therefore, S3 transports the dried materials to a crusher and grinds them into particles that can pass through a 200-mesh screen. After grinding, the mineral powder is poured into a blender, and silica powder is added. The amount of silica powder added is 10% of the dried mineral powder. After stirring evenly, an adhesive and phosphoric acid are added and stirred. After stirring for five minutes, an appropriate amount of water is added to adjust. After stirring for ten minutes, the molding viscosity and moisture are reached, and the valve at the bottom of the blender is opened to release the yellow phosphorus mineral powder. The adhesive uses a polymer adhesive. In this implementation, the QTHL-03 pellet adhesive of Xingtai Botai Technology Co., Ltd. is selected, and the amount used is 1% of the weight of the mixed mineral powder and silica powder. The amount of waste phosphoric acid is 2%.

[0052] S5: Ball pressing: The mixed ore is fed into a ball press to be pressed into wet phosphate rock powder pellets;

[0053] The mixed ore material in S5 is fed into the briquetting machine. The molding line pressure is 25MP, and the briquetting is 35 oval sphere with a diameter of 5 cm and a thickness of 3 mm. The molding machine has a lower line pressure than the metallurgical pelletizing machine. Pour the stirred yellow phosphate ore powder into the feed port at one time, start the molding machine, and connect the semi-finished wet ball at the end of the belt.

[0054] S6: Drying of phosphate rock pellets: Drying the wet phosphate rock pellets in an environment of 80-550°C to obtain phosphate rock pellets.

[0055] The wet bulbs dried in S6 are dried in a vertical dryer, and the flooding temperature is controlled as shown in the following table

[0056]

[0057] Table 2 Vertical Dryer

[0058] Example 2

[0059] The difference between Example 2 and Example 1 is that the natural plant-based polymer flocculant is an amphoteric starch-modified flocculant, specifically chlorohydroxypropyltrimethylammonium chloride substituted with carboxymethyl starch, its adhesive is Peridot, and the mineral powder drying temperature is controlled at 1200°C.

[0060] Example 3

[0061] The difference between Example 3 and Example 1 is that the natural plant-based polymer flocculant is a lignin derivative flocculant, and the mineral powder drying temperature is controlled at 1000°C.

[0062] Comparative Example 1

[0063] The difference between Comparative Example 1 and Example 1 is that phosphoric acid is not added after the adhesive is added.

[0064] Comparative Example 2

[0065] The difference between Comparative Example 2 and Example 1 is that its flocculant is an inorganic flocculant, which is prepared by compounding 20% ​​bentonite, 60% aluminum sulfate, and 20% ferrous sulfate; its adhesive is an organic adhesive, and the inorganic adhesive is phosphate and magnesium chloride, the mass percentage of the phosphate is 80%, and the mass percentage of the magnesium chloride is 20%; the inorganic adhesive is added in the form of solid powder, mixed evenly with phosphate rock powder, and then pressed into balls to obtain pellets.

[0066] Ten samples of pellets in each embodiment of the present application were taken and tested, and the data are as follows:

[0067] The wet ball strength (unit conversion KG) of the phosphate rock powder pellets produced is as follows:

[0068] Sample No. 1 2 3 4 5 6 7 8 9 10 average Example 1 23.2 24.2 24.9 23.4 24.7 24.5 23.7 25.1 23.9 23.8 24.14 Example 2 22.8 24.5 23.6 24.1 23.7 26.7 21.1 23.2 21.7 23.4 23.48 Example 3 22.1 23.8 22.9 24.6 23.1 21.9 22.7 24.6 25.8 22.1 23.36 Comparative Example 1 21.5 24.4 22.3 24.0 24.1 23.7 22.5 23.3 23.6 22.5 23.19

[0069] Table 3 Wet bulb strength

[0070] The dry ball strength of the phosphate rock powder pellets after drying (unit conversion KG) is as follows:

[0071]

[0072]

[0073] Table 4 Dry bulb strength

[0074] The taste data (percentage content of P2O5) of the phosphate rock powder pellets produced after drying are as follows:

[0075] Sample No. 1 2 3 4 5 6 7 8 9 10 average Example 1 39.4 32.2 34.1 33.2 28.9 34.8 36.1 34.7 29.8 33.1 33.63 Example 2 34.6 33.3 29.6 33.7 33.1 31.9 28.7 34.1 34.1 32.7 32.58 Example 3 33.7 31.7 34.5 29.6 32.8 33.7 32.9 33.8 33.8 33.6 33.01 Comparative Example 2 25.4 22.4 24.6 23.4 26.4 22.3 21.7 22.6 22.4 22.3 23.35

[0076] Table 4 Pellet taste

[0077] The above is only an embodiment of the present invention, and the common knowledge such as the known specific structure and characteristics in the scheme is not described in detail here. It should be pointed out that for those skilled in the art, several deformations and improvements can be made without departing from the structure of the present invention, which should also be regarded as the protection scope of the present invention, and these will not affect the effect of the implementation of the present invention and the practicality of the patent. The scope of protection required by this application shall be based on the content of its claims, and the specific implementation methods and other records in the specification can be used to interpret the content of the claims.

Claims

1. A method for producing phosphate rock powder pellets using yellow phosphate ore dressing slurry, characterized in that: The following steps are involved: S1: Slurry thickening: The ore pulp from the ore dressing is transported to the thickener for solid-liquid separation, and flocculants are added to flocculate the mineral powder in the ore pulp to obtain high-concentration ore pulp; S2: Filtration: The high-concentration slurry is transported to the filter press for filtration to obtain a ore powder filter cake; S3: Mineral powder drying: the mineral powder filter cake is passed into a dryer for drying at a drying temperature of 1000-1200°C to obtain dried mineral powder; S4: Proportional mixing: Mix the dried mineral powder and silica powder, the mass of the silica powder accounts for 8-12% of the dried mineral powder, and after mixing evenly, add 0.5-1% of the weight of the silica powder and the mineral powder and 1-3% of phosphoric acid to continue mixing, and mix for 5 minutes to obtain a mixed mineral material; S5: Ball pressing: The mixed ore is fed into a ball press to be pressed into wet phosphate rock powder pellets; S6: drying phosphate rock pellets: drying the wet phosphate rock pellets in an environment of 80-550°C to obtain phosphate rock pellets; The flocculant in S1 is a natural plant-based polymer flocculant, and the adhesive is an organic adhesive with hydroxyl groups.

2. The method for producing phosphate rock powder pellets using yellow phosphate rock powder according to claim 1, characterized in that: The natural plant-based high molecular weight flocculant is a modified guar gum-based sedimentation agent.

3. The method for producing phosphate rock powder pellets using yellow phosphate rock powder according to claim 1, characterized in that: The natural plant-based polymer flocculant is an amphoteric starch-modified flocculant, specifically chloropropyltrimethylammonium chloride substituted with carboxymethyl starch.

4. The method for producing phosphate rock powder pellets using yellow phosphate rock powder according to claim 1, characterized in that: The natural plant-based polymer flocculant is a lignin derivative flocculant.

5. The method for producing phosphate rock powder pellets using yellow phosphate rock powder according to claim 1, characterized in that: The adhesive is Peridot.

6. The method for producing phosphate rock powder pellets using yellow phosphate rock powder according to claim 1, characterized in that: The adhesive is QTHL-03 pellet adhesive.

7. The method for producing phosphate rock powder pellets using yellow phosphate rock powder according to claim 1, characterized in that: The S4 mix contains 1% adhesive and 2% phosphoric acid.

Images