Preparation method of phosphorus tailing-based high hydration resistance calcium magnesium particles

Abstract

The application provides a preparation method of phosphorus tailing-based high-hydrating-resistance calcium-magnesium refractory particles. The calcium-magnesium component is obtained by removing phosphorus through once reverse flotation, removing calcium-magnesium through one roughing-three scavenging-one cleaning direct flotation process, and then lightly burning the calcium-magnesium component after the calcium-magnesium component is made into a column-shaped test block. The calcium-magnesium component is ground, and water is sprayed during the granulation process to realize spherical particles. The spherical particles are dried and calcined to obtain high-hydrating-resistance calcium-magnesium refractory particles. The method is simple and low in cost, and the light burning temperature is low. No modifier is needed. The prepared calcium-magnesium particles have high refractoriness and good hydrating resistance. The calcium-magnesium particles can be mixed with high-quality magnesia to prepare magnesium-calcium bricks with high softening temperature under load, high high-temperature compressive strength and good corrosion resistance, and the calcium-magnesium phosphate tailings can be used with high added value, which brings new profit growth points for phosphorus chemical enterprises and promotes the sustainable development of the phosphorus chemical enterprises.

Description

TECHNICAL FIELD

[0001] The application relates to a phosphorus tailing-based high-hydration-resistance calcium-magnesium refractory particle preparation method, which is a high-value utilization method for calcium-magnesium components in industrial solid waste phosphorus tailings in phosphorus chemical production. BACKGROUND

[0002] Phosphorus tailings are large amounts of mining solid waste produced after ore dressing to extract concentrate in the phosphorus chemical industry, and most of them are stacked in tailings ponds. The stacking of phosphorus tailings will cause a series of environmental problems and safety problems, and will also bring huge financial and land pressure to enterprises, seriously restricting the sustainable development of enterprises.

[0003] At present, the main application direction of phosphorus tailings is building materials and aggregates, and the added value is low. Meanwhile, there are also studies on using phosphorus tailings to prepare refractory materials, but these studies often need to add titanium oxide, yttrium oxide, zirconium oxide and other additives, which greatly increases the cost, and the hydration resistance and high temperature performance cannot meet the clean steel smelting requirements.

[0004] The application designs a "purification-grinding-granulation-drying-calcination" process for phosphorus tailings, and a phosphorus tailing-based high-hydration-resistance calcium-magnesium refractory particle preparation method is obtained. SUMMARY

[0005] The application aims to provide a phosphorus tailing-based high-hydration-resistance calcium-magnesium refractory particle preparation method. The prepared calcium-magnesium particles have excellent hydration resistance and excellent high-temperature performance. The melting steel ingot test proves that the phosphorus element in the calcium-magnesium particles will not escape into the steel ingot, proving that the material can be applied to clean steel smelting as a new type of environmentally friendly refractory material. The technical scheme of the application comprises the following steps:

[0006] (1) Pretreatment of calcium-magnesium phosphorus tailings: after one reverse flotation for removing phosphorus, one roughing-three scavenging-one cleaning for flotation process for extracting calcium-magnesium, a calcium-magnesium component is obtained, and the thermogravimetric diagram of the calcium-magnesium component is as shown in Figure 1 ;

[0007] (2) The selected calcium-magnesium component is lightly calcined after being pressed into a cylindrical test block to obtain a lightly calcined calcium-magnesium component;

[0008] In some embodiments, the selected calcium-magnesium component is pressed into a cylindrical test block with a diameter of 50 and a height of 50 under a certain pressure

[0009] (3) The lightly calcined calcium-magnesium component is ground and then disc granulated, and water is sprayed during the granulation process until all the powder is formed into spherical particles; the spherical particles are dried and calcined to obtain high-hydration-resistance calcium-magnesium refractory particles.

[0010] The calcium magnesium component obtained in step (1) is 19-22% MgO, 30-35% CaO, 0.8-1.5% P2O5, 0.6-1.2% SiO2, and 0.1-0.3% Al2O3.

[0011] In step (2), the binding agent used to realize the cylindrical test block is selected from any one of anhydrous ethanol, anhydrous propanol, and anhydrous butanol; and the light burning temperature is 700-850°C.

[0012] After light burning and dry grinding, the particle size of the calcium magnesium component is less than 75 μm, so that it is fully dispersed and has good granulation property.

[0013] After grinding, water is sprayed at a rotation speed of 100-150 r / min, and when the calcium magnesium particles are realized, the rotation speed is reduced to 20-30 r / min.

[0014] The aqueous solution contains added phytic acid, and the amount of the added phytic acid is 10-30%.

[0015] Compared with the prior art, the present application has the following positive effects:

[0016] ① The present application processes the phosphorus tailings through "concentration - briquetting - light burning - grinding - granulation - secondary calcination", the light burning temperature is low, and high hydration resistance calcium magnesium refractory particles can be obtained without dead burning in the medium temperature treatment, no modifier such as zirconium oxide, titanium oxide, and yttrium oxide needs to be added in the preparation process, and the cost and energy consumption are low;

[0017] ② The calcium magnesium refractory particles prepared by the present application have a use temperature as high as 1800°C or above, and have stable high-temperature performance;

[0018] ③ The calcium magnesium refractory particles prepared by the present application can be mixed with high-quality magnesia to prepare magnesium calcium bricks with high softening temperature under load, high high-temperature compressive strength, and good corrosion resistance, and can be used as a new type of magnesium calcium refractory material raw material to help the green and sustainable development of the clean steel industry and the phosphorus chemical industry. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 TG-DSC curve of the calcium magnesium component obtained in the examples. DETAILED DESCRIPTION

[0020] The present application is further described below by listing several implementation examples, but is not limited to the examples.

[0021] Example 1

[0022] The calcium magnesium phosphate tailings sample is subjected to one-time reverse flotation for removing phosphorus-one rough three-sweeping one-precision positive flotation for extracting calcium magnesium flotation process to obtain calcium magnesium component meeting certain technical standards. The reverse flotation for removing phosphorus reagent system: sodium carbonate 8000 g / t, pH value is 9.7, P collector dosage is 200 g / t; the one-rough three-sweeping one-precision positive flotation for extracting calcium magnesium flotation reagent system: roughing sulfuric acid dosage is 12000 g / t, pH value is 4.5, Mg collector dosage is 200 g / t; sweeping I roughing sulfuric acid dosage is 4000 g / t, pH value is 4.5, Mg collector dosage is 200 g / t; sweeping II sulfuric acid dosage is 3000 g / t, pH value is 4.5; sweeping III sulfuric acid dosage is 3000 g / t, pH value is 4.5; the precision selection sulfuric acid dosage is 3000 g / t, pH value is 4.5, the obtained calcium magnesium component chemical analysis results are shown in Table 1, and the calcium magnesium component TG-DSC curve is shown in Figure 1

[0023] Table 1 Chemical multi-element analysis of calcium magnesium component after flotation treatment

[0024]

[0025] The refined calcium magnesium component is pressed into a φ50*50 cylindrical test block under the action of 20 MPa with anhydrous ethanol as the binder, and then the test block is placed in a calcination furnace at 850℃ for 4h to obtain the lightly calcined calcium magnesium component; the lightly calcined calcium magnesium component is dry ground in a ceramic ball mill for 15 min until the particle size is less than 75μm and the proportion is 80%. The ground calcium magnesium component is placed in a disc granulator, the rotating speed is 100r / min, water is sprayed onto the surface of the calcium magnesium component, when the granulation starts, the rotating speed is reduced to 30r / min until all the powder is formed into spherical particles; the prepared particles are dried in an oven at 110℃ for 10h; the fully dried particles are calcined in a high temperature furnace at 1600℃ for 8h to obtain the high hydration resistance calcium magnesium refractory particles.

[0026] The detected calcium magnesium refractory particle performance: refractoriness is greater than 1800℃, apparent porosity is 3.4%, bulk density is 3.09%, and hydration test weight gain rate is 1.7%.

[0027] The related technical scheme of example 1 is adopted, and the phytic acid aqueous solution with a mass concentration of 15% is sprayed onto the surface of the calcium magnesium component. The detected calcium magnesium refractory particle performance: refractoriness is greater than 1950℃, apparent porosity is 3.65%, bulk density is 3.65%, and hydration test weight gain rate is 1.4%.

[0028] Example 2

[0029] The calcium magnesium phosphate tailings sample is subjected to one-time reverse flotation for removing phosphorus-one rough three-sweeping one-precision positive flotation for extracting calcium magnesium flotation process to obtain calcium magnesium component meeting certain technical standards. The flotation reagent system and process are the same as those of example 1.​

[0030] The refined calcium-magnesium component is pressed into a φ50*50 cylindrical test block under 20 MPa with anhydrous ethanol as a binder, and then the test block is placed in a calciner at 800℃ for 5h to obtain the lightly calcined calcium-magnesium component; the lightly calcined calcium-magnesium component is dry ground in a ceramic ball mill for 20 min to a particle size of less than 75μm accounting for 90%.

[0031] The ground calcium-magnesium component is placed in a disc granulator with a rotating speed of 100r / min, and 30% mass concentration of a phytic acid aqueous solution is added to the surface of the calcium-magnesium component in a spray form; when granules begin to form, the rotating speed is reduced to 25r / min until all the powders are formed into spherical granules; the prepared granules are dried in an oven at 100℃ for 12h; and the fully dried granules are calcined in a high-temperature furnace at 1700℃ for 6h to obtain the high hydration resistance calcium-magnesium refractory granules.

[0032] The calcium-magnesium refractory granules have the following properties: refractoriness greater than 1900℃, apparent porosity of 3.3%, bulk density of 3.20%, and hydration test weight gain rate of 1.4%.

[0033] The prepared calcium-magnesium granules are mixed with high-quality magnesia to prepare calcium-magnesium bricks, and the high-temperature working properties are tested; the material ratio is shown in Table 2, and phenolic resin is used as a binder with an addition amount of 4% of the total amount of the materials.

[0034] Table 2 Material ratio of calcium-magnesium bricks

[0035]

[0036]

[0037] The materials are mixed and stirred by using a cement paste mixer, and then the materials are uniformly mixed and pressed into a cylindrical sample (φ35mm*50mm, a sample of 160mm*40mm*40mm, and a φ50mm crucible), vacuum dried and fired. The detection results show that the load softening temperature is 1600℃, the cold compressive strength is 67MPa, and the high-temperature bending strength is 50.2MPa. The steel ingot smelting test is conducted by using the fired crucible, and it is proved that the calcium-magnesium bricks used in the application meet the clean steel smelting requirements.

[0038] Example 3

[0039] The calcium-magnesium component meeting certain technical standards is obtained by the flotation process of one-time reverse flotation for removing phosphorus-one roughing-three scavenging-one cleaning for extracting calcium-magnesium. The flotation reagent system and process are the same as those in Example 1.

[0040] Using anhydrous ethanol as a binder, the selected calcium and magnesium components were pressed into cylindrical test blocks with a diameter of φ50*50 under 20MPa. The test blocks were then calcined at 850℃ for 4h to obtain lightly calcined calcium and magnesium components. The lightly calcined calcium and magnesium components were then dry-milled in a ceramic ball mill for 10min until the particle size was less than 75μm and accounted for 75%.

[0041] The pulverized calcium-magnesium components were placed in a disc granulator at a speed of 100 r / min. A 20% phytic acid solution was sprayed onto the surface of the calcium-magnesium components. When particles began to form, the speed was reduced to 20 r / min until all the powder was formed into spherical particles. The formed particles were placed in an oven and dried at 110℃ for 8 hours. The fully dried particles were then placed in a high-temperature furnace and calcined at 1700℃ for 6 hours to obtain calcium-magnesium refractory particles with high hydration resistance.

[0042] The calcium-magnesium refractory granules were tested and found to have the following properties: refractoriness greater than 1980℃, apparent porosity of 3.6%, bulk density of 3.14%, and weight gain of 1.5% in the hydration test.

[0043] The prepared calcium-magnesium granules were mixed with high-quality magnesia to prepare magnesia-calcium bricks, and their high-temperature working performance was tested. The material ratio is shown in Table 3. Phenolic resin was used as a binder, and the amount added was 4% of the total material.

[0044] Table 3 Material Proportioning Table for Calcium Magnesium Bricks

[0045]

[0046] The materials were mixed thoroughly using a cement paste mixer, and then pressed into shape under a 150MPa pressure press. Cylindrical specimen, 160mm×40mm×40mm specimen The crucible was vacuum dried and fired. Testing showed a softening temperature of 1600℃, a compressive strength of 68 MPa at room temperature, and a flexural strength of 47.5 MPa at high temperature. Steel ingot smelting tests were conducted using the pressed and fired crucible, demonstrating that the calcium-magnesium bricks used in this invention meet the requirements for clean steel smelting.

[0047] Using the above process steps, high hydration-resistant calcium-magnesium refractory particles were prepared without the use of phytic acid. They were then configured according to Table 3, mixed and pressed under the above process conditions. The load softening temperature was tested to be 1600℃, the room temperature compressive strength was 55MPa, and the high temperature flexural strength was 42.6MPa.

Claims

1. A method for preparing highly hydration-resistant calcium-magnesium particles based on phosphorus tailings, characterized in that, The main steps include the following: (1) Pretreatment of calcium-magnesium phosphate tailings: The calcium-magnesium phosphate tailings sample was subjected to a reverse flotation process to remove phosphorus, followed by a roughing, three-scavenging, and one-fine positive flotation process to extract calcium and magnesium components. (2) The selected calcium and magnesium components are made into columnar test blocks and then lightly calcined to obtain lightly calcined calcium and magnesium components. A binder is used to realize the columnar test blocks. The binder is selected from any one of anhydrous ethanol, anhydrous propanol, and anhydrous butanol. The light calcination temperature is 700~850℃. (3) The lightly calcined calcium magnesium components are ground and then granulated by disc. Water is sprayed during the granulation process to achieve spherical particles. The spherical particles are dried and then calcined to obtain calcium magnesium refractory particles with high hydration resistance. After grinding, water is sprayed at a speed of 100-150 r / min. When calcium and magnesium particles are formed, the speed is reduced to 20-30 r / min. Phytic acid is added to the spray water, and the mass concentration of phytic acid is 15-30%.

2. The method for preparing phosphorus tailings-based high hydration-resistant calcium-magnesium particles according to claim 1, characterized in that, The calcium and magnesium components obtained in step (1) are 19-22% MgO, 30-35% CaO, 0.8-1.5% P2O5, 0.6-1.2% SiO2, and 0.1-0.3% Al2O3.

3. The method for preparing phosphorus tailings-based high hydration-resistant calcium-magnesium particles according to claim 1, characterized in that, After light calcination and dry grinding, the particle size of the calcium and magnesium components is less than 75 μm.

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