CN101786867A - Preparation method for zirconium silicate ball - Google Patents

Abstract

A method for preparing zirconium silicate balls relates to a grinding medium. Provided is a method for preparing zirconium silicate balls by spray granulation, isostatic pressing molding and high-temperature sintering. Add grinding dispersant, admixture and dispersion medium to zircon sand, and grind to obtain slurry; granulate the slurry to obtain zirconium silicate particles; shape zirconium silicate particles to obtain zirconium silicate ball blank; Zirconium silicate balls are sintered to produce zirconium silicate balls. The prepared zirconium silicate balls have the advantages of high density, high strength, high sphericity and high wear resistance. The preparation process is simple, stable and reliable, and the production efficiency is high. It can form large-sized products and is convenient for industrialization. Through testing, the volume density of the obtained zirconium silicate balls is above 4.0 g/cm ³ , the degree of sphericity is above 90%, the Mohs hardness is above 7.4, and the compressive strength is above 750N. The ball is composed of dense zirconium silicate particles, rejecting capillary and cavity, and has greater density and extrusion strength than other similar beads.

Description

A kind of preparation method of zirconium silicate ball

technical field

The invention relates to a grinding medium, in particular to a method for preparing zirconium silicate balls.

Background technique

Ball mill is widely used in metallurgy, mining, electric power, building materials, chemical industry and other fields, and it is a kind of crushing equipment that is widely used. The grinding medium is the key to crushing materials in the ball mill. Its shape is generally a sphere or cylinder, and the materials are crushed by various complex movements such as rolling, impact, extrusion, and friction of the grinding medium in the ball mill. The quality of grinding media not only directly affects the level of production efficiency, but also affects the quality of products.

The rapid development of the ultrafine powder processing industry has driven the development and production of grinding media. The development of high-quality grinding media with high grinding efficiency will make a positive contribution to the powder processing industry and create huge economic benefits. At present, there are various grinding balls (beads) on the grinding media market, with different performances and prices. How users use suitable and best media to effectively reduce costs and improve processing efficiency has become a problem that cannot be ignored in the grinding industry. The diversity of products to be ground and the complexity of the production process determine the diversity of grinding media. A variety of grinding balls, such as glass beads, alumina balls, zirconium silicate beads, pure zirconium balls and chrome steel balls, etc., will occupy different positions in the market according to different processed products and places of use.

Commercial grinding measures usually use such as quartz sand, glass beads, ceramic media or steel balls as grinding media. Among them, the density of quartz sand and glass beads is very low, only 2.6g/cm ³ , and the hardness of glass beads is very low, which limits the materials that can be ground with quartz sand and glass beads. The use of small steel balls can only be limited when the iron contamination caused by the wear of small steel balls during the grinding process can be tolerated.

Zirconium balls generally refer to zirconium silicate (ZrSiO ₄ ) balls and zirconia (ZrO ₂ ) balls. The theoretical density of zirconium silicate is 4.6g/cm ³ , the Mohs hardness is 7-8, and the melting point is 2430°C, but it begins to decompose into ZrO ₂ and SiO ₂ at 1540°C. Zirconium silicate beads are composed of uniform and dense zirconium silicate grains with a low-melting _SiO2 glass phase at the grain boundaries. Among them, the content of zirconia is usually 64% to 70%. The excellent sphericity and medium density increase the grinding efficiency and reduce the wear of the equipment. It is suitable for materials with high viscosity and medium hardness (such as titanium dioxide, calcium carbonate, zirconium, etc.) Dispersion and grinding of quartz powder, kaolin, etc.).

The existing production techniques of zirconium silicate beads used as grinding media are basically high-temperature melting method and sintering method. The disadvantage of the melting method is that it is easy to form defects. Beads are formed in a high-temperature molten state. If a certain key technical parameter is not well controlled, the formed product will form defective and fragile beads: bubble beads, tail beads and flat (ellipse) beads. The above beads are easy to break during grinding because of the stress concentration area, so try to avoid too many such beads in the product when using them. The diameter of the ball produced by this method is difficult to enlarge, generally below 2mm. However, the sintering method is used to prepare zirconium silicate balls. The ball body is usually rolled and formed. The disadvantage is that it is difficult to prepare balls with high specific gravity, high hardness and low wear value. At present, Jiuzhou Grinding Media Co., Ltd. produces zirconium silicate balls by high-temperature melting method in China. Its products are mainly exported, with a particle size range of 0.2-2.5mm and a deviation of 0.2-0.4mm. However, domestic enterprises mainly use zirconium silicate balls imported from German Naino Company, with a particle size range of 0.4-2.8mm and a deviation of 0.2mm.

At present, the method of producing zirconium silicate balls abroad, such as NanorZr-64 zirconium silicate beads, is an advanced process of titration molding in electrolyte solution, high-temperature sintering and phasing. The beads are composed of dense zirconium silicate particles, which rejects Capillary and cavity, with greater density and extrusion strength than other similar beads, and its wear rate is 1/2 of the "melting" method beads. NanorZr-70 zirconium silicate beads are made by forming in electrolyte solution and firing at high temperature. The beads are composed of uniform and dense zirconium silicate grains, rejecting cavity beads, tail beads and snowman beads, etc.

The Chinese patent application No. 99118965.5 discloses a silicon-zirconium sphere manufacturing technology, which uses a method for producing silicon-zirconium microspheres by fusing zircon. In the method, the raw material added with co-solvent is smelted in a direct-current submerged arc furnace, and an air compressor is used to generate a high-number air flow for blowing to prepare silicon-zirconium spherical microbeads. The disadvantage of this method is that the size of the zirconium silicate balls is small and the particle size uniformity is poor.

So far, zirconium silicate balls with a diameter of more than 5 mm have been prepared by sintering, but due to immature technology, there are no satisfactory products on the market. Therefore, the development of high-quality zirconium silicate balls with a series of diameters will have a huge market prospect.

Contents of the invention

The object of the present invention is to provide a method for preparing zirconium silicate balls which adopt spray granulation, isostatic pressing molding and high-temperature sintering.

The technical solution of the present invention is to mix the zircon sand into ingredients, add a dispersant and an admixture, use deionized water as a dispersion medium, and mix uniformly by ball milling to obtain a stable slurry, then granulate the slurry with a spray dryer, and then The pellets are put into an isostatic press for molding, demolded to obtain a zirconium silicate ball blank, and finally the zirconium silicate ball blank is sintered at high temperature in an air atmosphere to obtain a zirconium silicate ball.

The present invention comprises the following steps:

1) Add grinding dispersant, admixture and dispersion medium to zircon sand, and obtain slurry after grinding;

2) granulating the slurry prepared in step 1) to obtain zirconium silicate particles;

3) molding the zirconium silicate particles obtained in step 2) to obtain a zirconium silicate ball blank;

4) Sintering the zirconium silicate ball green body obtained in step 3) to obtain the product zirconium silicate ball.

In step 1), in terms of mass percentage, the amount of grinding and dispersing agent can be 0.1% to 2% of the total slurry, the amount of admixture can be 3% to 10% of zircon sand, and the amount of dispersion medium can be It is 15% to 50% of zircon sand; the grinding and dispersing agent can be selected from polyacrylamide or ammonium citrate, etc., the admixture can be industrial alumina powder, etc., and the dispersion medium can be deionized water wait.

In step 2), the granulation can be granulated by a spray dryer, the process parameters of the granulation can be 250-300°C at the inlet temperature, and 110-150°C at the outlet temperature; the moisture content of the zirconium silicate particles is determined by mass The percentage can be 0.2%-2%, and the particle size of the zirconium silicate particles can be 100-280 mesh sieves.

In step 3), the molding can be formed by an isostatic pressing machine, the pressure can be 120-200 MPa, and the holding time can be 150-200s.

In step 4), the sintering can be carried out in an air atmosphere. The sintering temperature is to heat at a rate of 250-300°C/h to a temperature of 1450-1550°C. It is best to hold the temperature for 1 hour at an isothermal temperature. Let cool together.

The outstanding advantages of the present invention are: the prepared zirconium silicate balls have the advantages of high density, high strength, high sphericity and high wear resistance, the preparation process is simple, stable and reliable, high production efficiency, and can form large-sized products for easy industrialization. Through testing, the volume density of the obtained zirconium silicate balls is above 4.0 g/cm ³ , the degree of sphericity is above 90%, the Mohs hardness is above 7.4, and the compressive strength is above 750N. The ball is composed of dense zirconium silicate particles, rejecting capillary and cavity, and has greater density and extrusion strength than other similar beads. The product is competitive, convenient for industrial promotion, and has considerable market prospects.

Detailed ways

The present invention uses zircon sand as the raw material, the main component of the zircon sand is zirconium silicate (ZrSiO ₄ ), the content of ZrO ₂ is 62.38%-67.02%, the content of SiO ₂ is 31.74%-33.17%, and more than 1%. The particle size of other associated oxides is less than 0.18mm.

Example 1

1. Take the zircon sand imported from Australia and the commercially available industrial alumina powder as examples. The main component of zircon sand is zirconium silicate (ZrSiO ₄ ), the content of ZrO ₂ is 65.16%, the content of SiO ₂ is 32.64%, the content of Al ₂ O ₃ is 1.84%, the content of CaO is 1.01%, and there are other small amounts of Fe ₂ The particle size of O ₃ and TiO ₂ is less than 0.18mm. Commercially available industrial alumina powder has a purity >99.5% and an average particle size of 1 μm.

2. In the ball mill, the polypropyleneamide dispersant accounts for 2% of the slurry, the alumina powder admixture accounts for 8% of the zircon sand, and the deionized water as the dispersion medium accounts for 45% of the zircon sand. The ball mill is evenly mixed to obtain Stable slurry.

3. Send the slurry obtained in step 2) into a spray dryer for granulation, with an inlet temperature of 280-290°C and an outlet temperature of 130-140°C to produce zirconium silicate particles with a moisture content of 1%, and a particle size of 100-100°C. 280 mesh sieve pellets.

4. Fill the mold with the granules obtained in step 3), press isostatically at a pressure of 150 MPa, hold the pressure for 180 seconds, and then demould to obtain a zirconium silicate ball green body.

5. Sinter the zirconium silicate ball semi-finished product obtained in step 4) in an air atmosphere, heat at a rate of 280°C/h to an isothermal holding temperature of 1500°C, hold isothermally for 1 hour, and then cool the sample together with the furnace, that is The final zirconium silicate beads are obtained.

6. The bulk density of zirconium silicate balls in this embodiment is 4.4g/cm ³ , the diameter is 2.0mm (the diameter of the spherical cavity in the mold is 2.0mm), the degree of sphericity is 98%, the Mohs hardness is 7.7, and the hardness is 7.7. The compressive strength is 960N.

Example 2

Raw material and technological process are similar to embodiment 1. In the ball mill, the polypropyleneamide dispersant accounts for 1.5% of the slurry, the alumina powder additive accounts for 5% of the zircon sand, and the deionized water as the dispersion medium accounts for 30% of the zircon sand, so that a stable slurry is obtained. The slurry spray granulation, the inlet temperature is 280-290 °C, the outlet temperature is 125-135 °C, and the zirconium silicate particles with a moisture content of 1.2% are obtained, and the particle size is 100-280 mesh sieves to fill the mold, etc. Static pressure forming, pressure 150MPa, holding pressure 180s, heating at a speed of 280°C/h to the temperature of isothermal holding at 1500°C, holding isothermally for 1h. The volume density of the zirconium silicate balls in this example is 4.2g/cm ³ , the diameter is 5mm (the diameter of the spherical cavity in the mold is 5mm), the degree of sphericity is 98%, the Mohs hardness is 7.5, and the compressive strength is 900N.

Example 3

Raw material and technological process are similar to embodiment 1. In the ball mill, the polypropylene amide dispersant accounts for 1.0% of the slurry, the alumina powder admixture accounts for 8% of the zircon sand, and the deionized water as the dispersion medium accounts for 30% of the zircon sand, so that a stable slurry is obtained. The slurry spray granulation, the inlet temperature is 280-290 °C, the outlet temperature is 130-140 °C, and the zirconium silicate particles with a moisture content of 1.1% are produced, and the particle size is 100-280 mesh sieves to fill the mold, etc. Static pressure forming, pressure 150MPa, holding pressure 180s, heating at a speed of 270°C/h to the temperature of isothermal holding at 1500°C, holding isothermally for 1h. The bulk density of the zirconium silicate balls in this example is 4.4g/cm ³ , the diameter is 9.9mm (the diameter of the spherical cavity in the mold is 10mm), the degree of sphericity is 95%, the Mohs hardness is 7.6, and the compressive strength is 940N.

Example 4

Raw material and technological process are similar to embodiment 1. In the ball mill, the polypropyleneamide dispersant accounts for 1.0% of the slurry, the alumina powder additive accounts for 4% of the zircon sand, and the deionized water as the dispersion medium accounts for 45% of the zircon sand, so that a stable slurry is obtained. Spray granulation of the slurry, the inlet temperature is 275-285°C, the outlet temperature is 120-130°C, and the zirconium silicate particles with a moisture content of 1.4% are produced, and the particle size is 100-280 mesh sieves to fill the mold, etc. Static pressure forming, pressure 180MPa, holding pressure 200s, heating at a speed of 260°C/h to the temperature of isothermal holding at 1530°C, holding isothermally for 1h. The volume density of the zirconium silicate balls in this example is 4.1g/cm ³ , the diameter is 14.5mm (the diameter of the spherical cavity in the mold is 15mm), the degree of sphericity is 95%, the Mohs hardness is 7.4, and the compressive strength is 800N.

Example 5

Raw material and technological process are similar to embodiment 1. In the ball mill, the polypropylene amide dispersant accounts for 2% of the slurry, the alumina powder admixture accounts for 5% of the zircon sand, and the deionized water of the dispersion medium accounts for 25% of the zircon sand, so that a stable slurry is obtained. The slurry spray granulation, the inlet temperature is 280-290 ° C, the outlet temperature is 130-140 ° C, the zirconium silicate particles with a moisture content of 0.9% are produced, and the particle size is 100-280 mesh sieves to fill the mold, etc. Static pressure molding, pressure 130MPa, holding pressure 150s, heating at a speed of 280°C/h to the temperature of isothermal holding at 1500°C, holding isothermally for 1h. The zirconium silicate balls in this example have a bulk density of 4.0 g/cm ³ , a diameter of 19.5 mm (the diameter of the spherical cavity in the mold is 20 mm), a degree of sphericity of 95%, a Mohs hardness of 7.4, and a compressive strength of 760N.

Example 6

Raw material and technological process are similar to embodiment 1. In the ball mill, the polypropylene amide dispersant accounts for 0.5% of the slurry, the alumina powder admixture accounts for 8% of the zircon sand, and the deionized water of the dispersion medium accounts for 50% of the zircon sand, so that a stable slurry is obtained. The slurry spray granulation, the inlet temperature is 280-290 °C, the outlet temperature is 125-135 °C, and the zirconium silicate particles with a moisture content of 1.5% are prepared, and the particle size is 100-280 mesh sieves to fill the mold, etc. Static pressure forming, pressure 200MPa, holding pressure 200s, heating at a speed of 250°C/h to the temperature of isothermal holding at 1530°C, holding isothermally for 1h. The volume density of the zirconium silicate balls in this example is 4.3g/cm ³ , the diameter is 24mm (the diameter of the spherical cavity in the mold is 25mm), the degree of sphericity is 90%, the Mohs hardness is 7.6, and the compressive strength is 920N.

Example 7

Raw material and technological process are similar to embodiment 1. In the ball mill, the polypropylene amide dispersant accounts for 1.5% of the slurry, the alumina powder admixture accounts for 6% of the zircon sand, and the deionized water of the dispersion medium accounts for 35% of the zircon sand, so that a stable slurry is obtained. The slurry spray granulation, the inlet temperature is 280-285 °C, the outlet temperature is 130-140 °C, and the zirconium silicate particles with a moisture content of 0.8% are prepared, and the particle size is 100-280 mesh sieves to fill the mold, etc. Static pressure molding, pressure 130MPa, holding pressure 150s, heating at a speed of 300°C/h to the temperature of isothermal holding at 1480°C, holding isothermally for 1h. The volume density of the zirconium silicate balls in this example is 4.2g/cm ³ , the diameter is 28mm (the diameter of the spherical cavity in the mold is 30mm), the degree of sphericity is 90%, the Mohs hardness is 7.5, and the compressive strength is 860N.

Claims (10)

1. a preparation method of zirconium silicate ball, is characterized in that comprising the following steps: 1) Add grinding dispersant, admixture and dispersion medium to zircon sand, and obtain slurry after grinding; 2) granulating the slurry prepared in step 1) to obtain zirconium silicate particles; 3) molding the zirconium silicate particles obtained in step 2) to obtain a zirconium silicate ball blank; 4) Sintering the zirconium silicate ball green body obtained in step 3) to obtain the product zirconium silicate ball. 2. the preparation method of a kind of zirconium silicate ball as claimed in claim 1 is characterized in that in step 1), by mass percentage, the consumption of described grinding dispersant is 0.1%～2% of total slurry , the dosage of the admixture is 3%-10% of the zircon sand, and the dosage of the dispersion medium is 15%-50% of the zircon sand. 3. the preparation method of a kind of zirconium silicate ball as claimed in claim 1, is characterized in that in step 1), described grinding dispersant is selected from polyacrylamide or ammonium citrate. 4. the preparation method of a kind of zirconium silicate ball as claimed in claim 1, is characterized in that in step 1), described admixture is industrial aluminum oxide powder. 5. the preparation method of a kind of zirconium silicate ball as claimed in claim 1, is characterized in that in step 1), described dispersion medium is deionized water. 6. the preparation method of a kind of zirconium silicate ball as claimed in claim 1 is characterized in that in step 2), described granulation adopts spray drier granulation, and the process parameter of granulation is inlet temperature 250～ 300°C, outlet temperature 110-150°C. 7. The method for preparing zirconium silicate balls according to claim 1, characterized in that in step 2), the water content of the zirconium silicate particles is 0.2% to 2% by mass percentage. 8 . The method for preparing zirconium silicate balls according to claim 1 or 7 , characterized in that in step 2), the particle size of the zirconium silicate particles is 100-280 mesh sieve. 9. The preparation method of a kind of zirconium silicate ball as claimed in claim 1, it is characterized in that in step 3), said molding adopts isostatic press molding, the pressure is 120～200MPa, and the holding time is 150 ~200s. 10. The preparation method of a zirconium silicate ball as claimed in claim 1, characterized in that in step 4), the sintering adopts sintering in an air atmosphere, and the sintering temperature is 250-300° C./h Heating at a high speed to a temperature of 1450-1550°C, holding the temperature isothermally for 1 hour, and then cooling the sample together with the furnace.