A granulation method for titanium-containing fine powder

Abstract

The present invention relates to the technical field of the recovery and utilization of titanium-containing fine powder. Specifically, it relates to a granulation method for titanium-containing fine powder, which comprises the following steps: mixing the titanium-containing fine powder with dextrin and then grinding, then mixing the ground material with asphalt, performing spray granulation and the first screening, followed by drying and calcination, and finally performing the second screening on the calcined product to obtain the finished product; wherein, the titanium-containing fine powder includes a first titanium-containing powder and furnace gas ash, the first titanium-containing powder includes sorted titanium concentrate and / or titanium slag fine powder, and by mass percentage, the proportion of the material with a particle size below 160 mesh in the titanium-containing fine powder is ≥90%. By using the method of the present invention, there is no need to prepare mother balls, and spherical particles can be quickly formed by spraying a mist-like liquid. Moreover, the granulated product also has high strength in the medium and high temperature ranges and is not prone to pulverization.

Description

Technical Field

[0001] The present invention relates to the technical field of recovery and utilization of titanium-containing fine powder, and more specifically, to a granulation method for titanium-containing fine powder. Background Art

[0002] During the production of titanium dioxide by the chlorination process, titanium-containing fine powder is usually generated. For example, the sorted titanium concentrate obtained by sorting the chlorination waste residue, the titanium slag fine powder generated by crushing the titanium slag, and the furnace gas ash collected from the flue of the titanium slag furnace all belong to titanium-containing fine powder. The particle size is relatively fine, usually less than 160 mesh, which does not meet the raw material particle size requirements of the chlorination process and cannot be directly recycled. It needs to be granulated before recycling.

[0003] In the granulation process of titanium-containing fine powder, inorganic binders that can introduce impurities cannot be used. Organic binders mainly contain elements such as carbon, hydrogen, and oxygen. They will carbonize and volatilize in the medium and high temperature sections, affecting the strength of the product. It is easy to powder during the dynamic calcination process in the rotary kiln, resulting in a reduction in the product yield. At the same time, the powdering rate during the production of titanium dioxide by the chlorination process will also increase, affecting the resource utilization of titanium-containing fine powder. In addition, most of the existing granulation methods require the preparation of mother balls, with a long process flow and cumbersome operation, which is not conducive to industrial production. Therefore, it is of great significance to provide a granulation method for titanium-containing fine powder that does not require the preparation of mother balls, can achieve granulation, has a certain strength in the medium and high temperature sections, and the product is not easy to powder.

[0004] In view of this, the present invention is specifically proposed. Summary of the Invention

[0005] The purpose of the present invention is to provide a granulation method for titanium-containing fine powder, which uses dextrin to quickly form balls and uses it as a low-temperature binder, uses asphalt as a medium and low-temperature binder to ensure the strength in the medium and low temperature sections, adds furnace gas ash, realizes resource utilization while improving the strength in the high temperature section. The method of the present invention does not require the preparation of mother balls, and can quickly form balls by spraying a mist-like liquid. Moreover, the granulated product also has high strength in the medium and high temperature sections and is not easy to powder.

[0006] In order to achieve the above object of the present invention, the following technical solutions are specifically adopted:

[0007] A granulation method for titanium-containing fine powder, comprising the following steps:

[0008] Mix the titanium-containing fine powder with dextrin and grind, then mix the ground material with asphalt, perform spray granulation and the first screening, then carry out drying and calcination, and perform the second screening on the calcined product to obtain the product;

[0009] Wherein, the titanium-containing fine powder includes a first titanium-containing powder and furnace gas ash, the first titanium-containing powder includes sorted titanium concentrate and / or titanium slag fine powder, and by mass percentage, the proportion of materials with a particle size below 160 mesh in the titanium-containing fine powder is ≥90%.

[0010] Preferably, the mass percentage of the furnace gas ash in the titanium-containing fine powder is 10%-30%.

[0011] Preferably, the first titanium-containing powder includes the separated titanium concentrate and the titanium slag fine powder. The mass percentage of the separated titanium concentrate in the titanium-containing fine powder is 30%-50%, and the mass percentage of the titanium slag fine powder in the titanium-containing fine powder is 30%-50%.

[0012] Preferably, by mass percentage, the addition amount of the dextrin accounts for 2%-5% of the titanium-containing fine powder.

[0013] Preferably, the dextrin includes at least one of yellow dextrin, white dextrin, and British gum.

[0014] Preferably, by mass percentage, the material below 325 mesh in the ground material accounts for ≥95%.

[0015] Preferably, by mass percentage, the addition amount of the asphalt accounts for 3%-5% of the titanium-containing fine powder.

[0016] Preferably, the particle size of the material entering the drying process after the first screening is 20-160 mesh.

[0017] Preferably, the material less than 160 mesh after the first screening is returned to the spray granulation process, the material greater than 20 mesh is crushed, the material with a particle size of 20-160 mesh after crushing enters the drying process, and the material less than 160 mesh after crushing is returned to the spray granulation process.

[0018] Preferably, the drying temperature is 105-180°C, and the drying time is 1-2 h.

[0019] Preferably, the calcination temperature is 300-1300°C, and the calcination time is 3-5 h.

[0020] Preferably, the calcination is carried out in a rotary kiln.

[0021] Preferably, the particle size of the product obtained after the second screening is 20-160 mesh.

[0022] Preferably, the materials greater than 20 mesh and less than 160 mesh after the second screening are returned to the grinding process.

[0023] Preferably, the method of spray granulation is as follows: Place the mixture of the titanium-containing fine powder, dextrin, and asphalt in a granulation container. While the granulation container is rotating, evenly spray a mist-like liquid onto the material, and the material forms spheres after contacting the mist-like liquid to achieve granulation.

[0024] Preferably, the spray granulation is carried out in a sugar coating machine.

[0025] Preferably, the titanium grade of the titanium-containing fine powder is ≥75%.

[0026] Preferably, the titanium grade of the separated titanium concentrate is ≥86%, the mass percentage content of calcium oxide is <0.13%, and the mass percentage content of silicon dioxide is 3%-8%.

[0027] Preferably, the titanium grade of the titanium slag fine powder is ≥81%, and the mass percentage content of silicon dioxide is <3%.

[0028] Preferably, the titanium grade of the furnace gas ash is ≥45%, the mass percentage content of silicon dioxide is 8%-13%, the mass percentage content of aluminum oxide is 1.5%-3%, and the mass percentage content of manganese oxide is 3%-6%.

[0029] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0030] (1) After the titanium-containing fine powder and dextrin are mixed and ground by the method of the present invention, there is no need to prepare mother balls, and spherical particles can be quickly formed by spraying a mist-like liquid. At the same time, asphalt is added as a medium and low temperature binder, and the loss on ignition at 400-600 °C is about 45%, and about 55% can still play a bonding role, ensuring the strength in the medium and low temperature range (400-600 °C). The furnace gas ash can sinter with the materials at or above 600 °C, realizing the reuse of waste while improving the strength in the high temperature range, making the granulated product not easy to powder.

[0031] (2) The method of the present invention can resourcefully utilize the separated titanium concentrate from the waste residue generated in the production of titanium dioxide by the chlorination method, the titanium slag fine powder generated by crushing the titanium slag, and the furnace gas ash collected from the titanium slag furnace flue, reducing the waste residue discharge, saving resources and reducing environmental pollution at the same time. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for the description of the specific embodiments or the prior art. Obviously, the following drawings are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0033] Figure 1 It is the granulation process flow chart provided by the embodiment of the present invention;

[0034] Figure 2 It is the loss on ignition result chart of the yellow dextrin binder and the asphalt binder used in the embodiment of the present invention at different temperature ranges. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0035] The technical solution of the present invention will be clearly and completely described below in conjunction with the accompanying drawings and specific embodiments. However, those skilled in the art will understand that the following described embodiments are some embodiments of the present invention, rather than all embodiments, and are only used to illustrate the present invention and should not be regarded as limiting the scope of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention. For those conditions not specified in the embodiments, they are carried out according to conventional conditions or conditions recommended by the manufacturer. For reagents or instruments without indicating the manufacturer, they are all conventional products that can be obtained through commercial purchase.

[0036] As Figure 1 shown, the present invention provides a granulation method for titanium-containing fine powder, comprising the following steps:

[0037] Mix the titanium-containing fine powder with dextrin and then grind it. Then mix the ground material with asphalt, perform spray granulation and the first screening, followed by drying and calcination, and perform the second screening on the calcined product to obtain the product;

[0038] Among them, the titanium-containing fine powder includes a first titanium-containing powder and furnace gas ash. The first titanium-containing powder includes sorted titanium concentrate and / or titanium slag fine powder. By mass percentage, the proportion of the material with a particle size below 160 mesh in the titanium-containing fine powder is ≥90%.

[0039] The method of the present invention uses dextrin as a low-temperature binder. After mixing, the material does not need to prepare mother balls, and directly spraying a misty liquid can quickly form balls. Grinding the titanium-containing fine powder with dextrin can make the titanium-containing fine powder and the binder fully contact. At the same time, the dextrin binder can play a lubricating role, making the surface of the fine powder smooth and enabling quick ball formation during rolling granulation; the bonding mechanism of dextrin belongs to the adsorption theory, and the bonding force mainly comes from intermolecular forces (van der Waals forces and hydrogen bonds). Dextrin can be carbonized and basically completely volatilized at 300°C. As Figure 2 shown, when the yellow dextrin binder is heated from 300°C to 400°C (30 min), its loss on ignition has reached 83.3%. It cannot play a good bonding role above 400°C, which will cause the strength of the material to deteriorate and the material to powder; therefore, asphalt is added as a medium-low temperature binder. At 400-600°C, as the temperature rises, although asphalt will decompose, carbon remains, which can form a carbon binding phase, thereby improving the strength. As Figure 2As shown, when the asphalt is heated from 400°C to 600°C (60 min), its loss on ignition is about 45%, and about 55% can still play a binding role, ensuring the strength in the medium and low temperature range of 400 - 600°C; as the temperature continues to rise above 600°C, the loss of asphalt will also become higher and higher. By 850°C, it will be completely carbonized, and the strength of the material will deteriorate and powder. Therefore, furnace gas ash is added to the raw materials. When approaching 600°C or above 600°C, aluminum and manganese in the furnace gas ash can sinter with the material, improving the strength of the material. The bonding mechanism of the furnace gas ash belongs to the chemical bond formation theory, with high strength, which can improve the strength of the material in the high temperature section. In addition, as a waste by-product of the titanium slag furnace, adding furnace gas ash can not only improve the strength of the material but also realize the resource utilization of waste by-products, avoiding stacking waste and environmental pollution.

[0040] Figure 2 It is a test chart of the loss on ignition of yellow dextrin binder and asphalt binder in different temperature ranges. The temperature range on the abscissa represents the starting temperature - ending temperature, and the loss on ignition time is 30 min / 100°C. For example, 300 - 400°C means the starting temperature is 300°C, and it ends after heating to 400°C in 30 min; 400 - 600°C means the starting temperature is 400°C, and it ends after heating to 600°C in 60 min.

[0041] During the preparation process, the asphalt cannot be ground together with titanium-containing fine powder and dextrin, which will cause the final mixture to be not smooth and unable to form balls quickly. The titanium-containing fine powder and dextrin must be mixed and ground first, and then mixed with the asphalt.

[0042] Using the granulation method of the present invention, there is no need to prepare mother balls, the process is simple, which is convenient for industrial production, and the strength of the granulated product is high, it is not easy to powder during the dynamic calcination process in the rotary kiln, the yield of qualified particle size products is high, and the powdering rate under high temperature and high gas velocity is low, which can reduce the powdering rate in the production process of the chlorination method and improve the quality and utilization rate of the raw materials for the chlorination method.

[0043] In some specific embodiments of the present invention, the sorted titanium concentrate is the titanium concentrate selected after sorting the upper discharge slag of the chlorination method, the titanium slag fine powder is the fine powder below 160 meshes generated during the crushing of the titanium slag furnace smelting slag block, and the furnace gas ash is the dust collected after coming out with the flue gas during the smelting of the titanium slag furnace. The method of the present invention can realize the recycling and reuse of waste by-products, save costs, and reduce environmental pollution.

[0044] In some specific embodiments of the present invention, the mass percentage content of the furnace gas ash in the titanium-containing fine powder is 10% - 30%, such as any one value or the range value composed of any two point values among 10%, 15%, 20%, 25%, 30%.

[0045] Since the titanium grade of furnace gas ash is relatively low, and the mass percentage of titanium dioxide usually does not exceed 60%, excessive use of furnace gas ash will cause the titanium grade of the mixed material for granulation to decrease, which does not meet the requirements of the chlorination process for the titanium grade of raw materials. In addition, excessive furnace gas ash will also cause too high silicon content. If the silicon is in the high-titanium slag, such as silicate, this part of the silicon can be chlorinated into silicon tetrachloride, which will be carried into the tail gas system to block the tail gas system, resulting in a large system pressure difference and tripping; if the silicon is of quartz type, it is not easily chlorinated and will accumulate in the chlorination furnace bed layer, causing the bed layer height to rise, reducing the titanium content, resulting in the risk of chlorine penetration and affecting normal startup. Therefore, the silicon content needs to be controlled. Too little furnace gas ash will cause poor high-temperature calcination strength and the product is prone to powdering; therefore, the amount of furnace gas ash used needs to be reasonably controlled.

[0046] In some specific embodiments of the present invention, the first titanium-containing powder includes the sorted titanium concentrate and the titanium slag fine powder. The mass percentage of the sorted titanium concentrate in the titanium-containing fine powder is 30%-50%, for example, any one value or a range value composed of any two values among 30%, 35%, 40%, 45%, 50%; the mass percentage of the titanium slag fine powder in the titanium-containing fine powder is 30%-50%, for example, any one value or a range value composed of any two values among 30%, 35%, 40%, 45%, 50%.

[0047] In some specific embodiments of the present invention, by mass percentage, the addition amount of the dextrin accounts for 2%-5% of the titanium-containing fine powder, for example, any one value or a range value composed of any two values among 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%.

[0048] Too little addition amount of dextrin is not suitable for molding, and too much addition amount will cause cost increase. In order to reduce the cost while ensuring the molding effect, the amount of dextrin used needs to be controlled within a suitable range.

[0049] In some specific embodiments of the present invention, the dextrin includes at least one of yellow dextrin, white dextrin, and British gum.

[0050] In some specific embodiments of the present invention, by mass percentage, the material below 325 mesh in the ground material accounts for ≥95%. The purpose is to ensure sufficient grinding, make the titanium-containing fine powder fully contact with the dextrin binder, and make the dextrin play a sufficient lubricating role.

[0051] In some specific embodiments of the present invention, the grinding can be at least one of vibration mill grinding or ball milling.

[0052] In some specific embodiments of the present invention, by mass percentage, the addition amount of the asphalt accounts for 3%-5% of the titanium-containing fine powder, such as any point value among 3%, 3.5%, 4%, 4.5%, 5% or the range value composed of any two point values; if the amount of asphalt used is too small, the strength in the temperature range of 400-600 °C is relatively low, and if the amount of asphalt used is too high, it will lead to an increase in cost and the inability to form balls quickly during the granulation stage.

[0053] In some specific embodiments of the present invention, the particle size of the material entering the drying process after the first screening is 20-160 mesh; this particle size range is set according to the target particle size after granulation, and the target particle size after granulation in the present invention is 20-160 mesh.

[0054] In some specific embodiments of the present invention, the material less than 160 mesh after the first screening is returned to the spray granulation process, and the material greater than 20 mesh is crushed. After crushing, the material with a particle size of 20-160 mesh enters the drying process, and the material less than 160 mesh after crushing is returned to the spray granulation process. This method can recycle the materials that do not meet the particle size requirements, improve the utilization rate of raw materials, avoid waste, and increase the yield.

[0055] In some specific embodiments of the present invention, the drying temperature is 105-180 °C, such as any point value among 105 °C, 110 °C, 120 °C, 130 °C, 140 °C, 150 °C, 160 °C, 170 °C, 180 °C or the range value composed of any two point values, and the drying time is 1-2 h, such as any point value among 1 h, 1.5 h, 2 h or the range value composed of any two point values.

[0056] Drying within this temperature range can, firstly, remove moisture, and secondly, the softening point of the asphalt is low, and drying at this temperature can turn it into a liquid phase, fully contacting the titanium-containing fine powder, and playing a solidifying role after cooling. However, it should be noted that within this temperature range, the formed material particles will not soften and remain in a relatively hard state, so there will be no adhesion between the material particles. Only the asphalt binder will turn into a liquid phase, making its distribution more uniform inside the particles, thereby improving the strength of the particles.

[0057] In some specific embodiments of the present invention, the calcination temperature is 300-1300 °C, and the calcination time is 3-5 h, such as any point value among 3 h, 3.5 h, 4 h, 4.5 h, 5 h or the range value between any two point values.

[0058] In some specific embodiments of the present invention, the calcination is variable-temperature calcination. As an example, the calcination starts at an initial temperature of 300 - 500°C. For example, the initial calcination temperature can be any point value among 300°C, 350°C, 400°C, 450°C, 500°C or a range value composed of any two point values. The final temperature is 1100 - 1300°C. For example, the final calcination temperature can be any point value among 1100°C, 1150°C, 1200°C, 1250°C, 1300°C or a range value composed of any two point values. The heating time is set at 100 - 125°C / 30min. After heating to the final temperature, the calcination ends.

[0059] In some other specific embodiments of the present invention, the calcination can also be isothermal calcination. The temperature of the isothermal calcination can be any point value among 1000°C, 1100°C, 1200°C, 1300°C or a range value composed of any two point values.

[0060] In some specific embodiments of the present invention, the calcination is carried out in a rotary kiln.

[0061] In some specific embodiments of the present invention, the particle size of the product obtained after the second screening is 20 - 160 mesh. The chlorination process for producing titanium dioxide requires the particle size of the raw material to be 20 - 160 mesh. Screening the materials within this particle size range can meet the requirements of the chlorination process for the raw material.

[0062] In some specific embodiments of the present invention, the materials larger than 20 mesh and smaller than 160 mesh after the second screening are returned to the grinding process to recycle the materials with unqualified particle sizes. Since the first screening has been carried out before drying, there are almost no materials larger than 20 mesh during the second screening. Only when there are problems in the first screening, there may be a small amount of materials larger than 20 mesh, which can be screened out during the second screening to further improve the product quality.

[0063] In some specific embodiments of the present invention, the method of spray granulation is as follows: Place the titanium-containing fine powder and the mixture of dextrin and asphalt in a granulation container. While the granulation container is rotating, evenly spray a mist-like liquid onto the materials. After the materials come into contact with the mist-like liquid, they form balls to achieve granulation.

[0064] When spraying the liquid, it must be in a mist-like state, not in a liquid state, and it should be sprayed onto the fine powder of the materials, not onto the inner wall of the granulation container to prevent irregular shapes. As an example, the mist-like liquid is water mist.

[0065] In some specific embodiments of the present invention, the spray granulation is carried out in a sugar coating machine. The mixed material is placed in the pot body of the sugar coating machine for rolling granulation. The rotational speed of the pot body is 25 - 40 r / min, such as any one value among 25 r / min, 30 r / min, 35 r / min, 40 r / min or the range value composed of any two point values.

[0066] In some specific embodiments of the present invention, the titanium grade of the titanium-containing fine powder is ≥ 75%, such as 75.75%, 79%, 82.82%, etc.

[0067] In some specific embodiments of the present invention, the titanium grade of the separated titanium concentrate is ≥ 86%, such as 86.61%, 87.32%, 88.13%, 88.44%, 88.76%, 88.83%, 89.57%, 90.02%, 90.63%, 91.48%, etc.; the mass percentage content of calcium oxide is < 0.13%, and the mass percentage content of silicon dioxide is 3% - 8%.

[0068] In some specific embodiments of the present invention, the titanium grade of the titanium slag fine powder is ≥ 81%, such as 81.19%, 81.60%, 81.82%, 82%, 82.50%, 83.1%, 83.76%, etc.; the mass percentage content of silicon dioxide is < 3%.

[0069] In some specific embodiments of the present invention, the titanium grade of the furnace gas ash is ≥ 45%, such as 46.80%, 47.59%, 48.10%, 51.71%, 53.33%, 53.82%, 54.44%, 55.19%, etc.; the mass percentage content of silicon dioxide is 8% - 13%, the mass percentage content of aluminum oxide is 1.5% - 3%, and the mass percentage content of manganese oxide is 3% - 6%.

[0070] In the present invention, the titanium grade refers to the mass percentage content of titanium dioxide.

[0071] The following combines specific embodiments to make a detailed description of some embodiments of the present invention. The raw material substances used in the embodiments can be obtained through commercial purchase without special instructions.

[0072] Example 1

[0073] The titanium-containing fine powder raw material used in this example includes the following components by mass percentage:

[0074] Separated titanium concentrate: TiO2 88.83%, Fe2O3 0.78%, CaO 0.09%, MgO 0.07%, SiO2 6.71%, Al2O3 0.26%, MnO 1.09%, and the balance is impurities.

[0075] Titanium slag fine powder: TiO2 81.72%, Fe2O3 7.27%, CaO 0.30%, MgO 0.81%, SiO22.72%, Al2O3 1.90%, MnO 1.98%, and the remainder is impurities.

[0076] Furnace gas ash: TiO2 53.9%, Fe2O3 24.61%, CaO 0.18%, MgO 1.2%, SiO2 10.2%, Al2O31.94%, MnO 4.71%, and the remainder is impurities.

[0077] The titanium concentrate, titanium slag fine powder and furnace gas ash are mixed in a ratio of 4:4:2 to obtain titanium-containing fine powder. The composition of the titanium-containing fine powder is as follows by mass percentage: TiO2 79.00%, Fe2O3 8.14%, CaO 0.19%, MgO 0.59%, SiO25.81%, Al2O3 1.25%, MnO 2.17%, and the remainder is impurities.

[0078] Granulation process:

[0079] The dried sorted titanium concentrate is mixed with titanium slag fine powder and furnace gas ash in a cement mortar mixer at a ratio of 4:4:2 for 8 minutes to obtain titanium-containing fine powder, and then yellow dextrin binder is added to the titanium-containing fine powder, the addition amount is 3.5% of the mass of the titanium-containing fine powder, and the mixing is continued for 8 minutes. The mixed material is ground in a vibration mill for 100s, and the proportion of less than 325 mesh is more than 95%. Then asphalt is added to the ground material, and the addition amount of asphalt is 3% of the mass of the titanium-containing fine powder. It is mixed in a cement mortar mixer for 8 minutes to obtain a mixed titanium-containing material with an added binder. The mixed titanium-containing material with an added binder is granulated in a water chestnut-type sugar coating machine, and a Sata spray gun is used to spray water at an atomization angle and water vapor onto the surface of the material. The granulation and balling time is 1h. After all the small balls are formed, the water spraying is stopped, and the pot body is continued to roll for 1h, with a pot body speed of 35r / min and an inclination angle of 45°. The granulated material is subjected to the first screening to screen out qualified materials of 20-160 mesh, and the materials less than 160 mesh are returned to the spray granulation process for reuse. The materials greater than 20 mesh are crushed, and the materials less than 160 mesh after crushing are also returned to the spray granulation process for reuse. The crushed materials of 20-160 mesh are dried at 105°C for 1.5h together with the qualified materials screened out by the first screening. The dried materials are put into a rotary kiln with a rotary kiln speed of 1.5r / min, with 300°C as the starting temperature and 1100°C as the ending temperature. The calcination is completed by heating from 300°C to 1100°C for 3.5h. The calcined materials are subjected to the second screening, and the particles of 20-160 mesh are screened out as qualified products, and the products with unqualified particle size are returned to the grinding process for reuse.

[0080] Example 2

[0081] Example 2 is similar to Example 1, with the only difference being that the starting temperature of calcination is 400 °C, and it is heated from 400 °C to 1100 °C for 3 hours until the calcination ends, and the other conditions are the same as those in Example 1.

[0082] Example 3

[0083] Example 3 is similar to Example 1, with the only difference being that the starting temperature of calcination is 500 °C, the ending temperature is 1200 °C, and it is heated from 500 °C to 1200 °C for 3 hours until the calcination ends, and the other conditions are the same as those in Example 1.

[0084] Example 4

[0085] Example 4 is similar to Example 2, with the only difference being that the addition amount of asphalt is 4% of the titanium-containing fine powder, and the other conditions are the same as those in Example 2.

[0086] Example 5

[0087] The difference between Example 5 and Example 2 lies in the composition and proportion of the titanium-containing fine powder raw material and the addition amount of yellow dextrin.

[0088] The titanium-containing fine powder raw material used in Example 5, calculated by mass percentage, includes the following components:

[0089] Sorted titanium concentrate: TiO2 90.63%, Fe2O3 0.87%, CaO 0.11%, MgO 0.06%, SiO2 3.72%, Al2O3 0.22%, MnO 1.24%, and the balance is impurities.

[0090] Titanium slag fine powder: TiO2 81.89%, Fe2O3 6.90%, CaO 0.28%, MgO 0.79%, SiO2 2.55%, Al2O3 1.80%, MnO 1.89%, and the balance is impurities.

[0091] Furnace gas ash: TiO2 52.68%, Fe2O3 26.12%, CaO 0.23%, MgO 1.55%, SiO2 8.83%, Al2O3 2.35%, MnO 5.81%, and the balance is impurities.

[0092] The sorted titanium concentrate, titanium slag fine powder, and furnace gas ash are mixed in a ratio of 3:4:3 to obtain the titanium-containing fine powder. Calculated by mass percentage, the composition of the titanium-containing fine powder is: TiO2 75.75%, Fe2O3 10.86%, CaO 0.21%, MgO 0.80%, SiO2 4.79%, Al2O3 1.49%, MnO 2.87%, and the balance is impurities.

[0093] The addition amount of yellow dextrin is 3% of the mass of the titanium-containing fine powder, and the other conditions are the same as those in Example 2.

[0094] Example 6

[0095] The difference between Example 6 and Example 5 is only the composition and proportion of the titanium-containing fine powder raw materials, and the remaining conditions are the same as those in Example 5.

[0096] The titanium-containing fine powder raw material used in Example 6, by mass percentage, includes the following components:

[0097] Sorted titanium concentrate: TiO2 90.02%, Fe2O3 0.52%, CaO 0.10%, MgO 0.06%, SiO2 5.00%, Al2O3 0.24%, MnO 1.35%, and the balance is impurities.

[0098] Titanium slag fine powder: TiO2 81.60%, Fe2O3 7.35%, CaO 0.30%, MgO 0.77%, SiO2 2.87%, Al2O3 1.94%, MnO 2.00%, and the balance is impurities.

[0099] Furnace gas ash: TiO2 51.71%, Fe2O3 24.43%, CaO 0.26%, MgO 1.54%, SiO2 11.03%, Al2O3 2.67%, MnO 6.00%, and the balance is impurities.

[0100] Mix the sorted titanium concentrate, titanium slag fine powder and furnace gas ash in a ratio of 5:4:1 to obtain the titanium-containing fine powder. By mass percentage, the composition of the titanium-containing fine powder is: TiO2 82.82%, Fe2O3 5.64%, CaO 0.20%, MgO 0.49%, SiO2 4.75%, Al2O3 1.16%, MnO 2.08%, and the balance is impurities.

[0101] Comparative Example 1

[0102] Comparative Example 1 is similar to Example 2, and the difference is only that: no asphalt binder is added, and the remaining conditions are the same as those in Example 2.

[0103] Comparative Example 2

[0104] Comparative Example 2 is similar to Example 5, and the difference is only that: no furnace gas ash and asphalt are added, and the mass ratio of the sorted titanium concentrate to the titanium slag fine powder is 3:4, and the remaining conditions are the same as those in Example 5.

[0105] Comparative Example 3

[0106] Comparative Example 3 is similar to Example 5, and the difference is only that: no asphalt is added, the furnace gas ash is replaced with an equal amount of sorted titanium concentrate, and the mass ratio of the sorted titanium concentrate to the titanium slag fine powder is 6:4, and the remaining conditions are the same as those in Example 5.

[0107] Comparative Example 4

[0108] Comparative Example 4 is similar to Example 5, with the only difference being that furnace gas ash was not added, and the mass ratio of the separated titanium concentrate to titanium slag fine powder was 3:4. Other conditions were the same as in Example 5.

[0109] Comparative Example 5

[0110] Comparative Example 5 is similar to Example 5, with the only difference being that asphalt was not added. Other conditions were the same as in Example 5.

[0111] Comparative Example 6

[0112] Comparative Example 6 is similar to Example 1, with the only difference being that the titanium-containing fine powder was ground together with yellow dextrin and asphalt, and the material agglomerated or formed flakes during the grinding process, making it impossible to carry out subsequent spray granulation.

[0113] Comparative Example 7

[0114] Comparative Example 7 is similar to Example 1, with the only difference being that yellow dextrin was not added, and water mist was sprayed onto the mixture of titanium-containing fine powder and asphalt, and no pellets were formed, making granulation impossible.

[0115] Experimental Example

[0116] 1. Test the yield of products with particle sizes of 20 - 160 mesh after dynamic calcination in a rotary kiln during the granulation process for Examples 1 - 6 and Comparative Examples 1 - 5. That is, the mass percentage of products with particle sizes of 20 - 160 mesh after dynamic calcination in a rotary kiln in the total calcined products. Since the calcination process in the rotary kiln is dynamic calcination, the material particles will continuously collide during the calcination process, and the materials with low strength will be pulverized, resulting in a decrease in the yield of products with particle sizes of 20 - 160 mesh. Therefore, the yield of products with particle sizes of 20 - 160 mesh during the dynamic calcination process in a rotary kiln can, to a certain extent, reflect the strength of the products. The test results are shown in Table 1.

[0117] Table 1

[0118]

[0119]

[0120] 2. Test the strength of the products in Examples 1 - 6 and Comparative Examples 1 - 5 during calcination at different temperature ranges

[0121] In production, the rotary kiln calcination is a dynamic process, while in experimental research, the muffle furnace calcination is often used, which is a static process. To simulate the dynamic process, the muffle furnace is used for static calcination at different temperature ranges. Then, the yield of the 20 - 160 mesh product after static calcination in different temperature ranges is sieved and calculated as the static yield for the corresponding temperature range. Then, the qualified materials of 20 - 160 mesh after static calcination in the corresponding temperature range are dropped from a height of 1.6 meters for 10 times to simulate the dynamic process. Then, the yield of the 20 - 160 mesh product after dropping 10 times from 1.6 meters is sieved and calculated as the dynamic yield for the corresponding temperature range. The comprehensive yield for the corresponding temperature range is calculated according to "Comprehensive yield = Static yield × Dynamic yield", and the strength of the corresponding temperature range is represented by the comprehensive yield of each temperature range. The total comprehensive yield for the entire calcination temperature range is calculated according to "Total comprehensive yield = Product of the comprehensive yields of each temperature range", which represents the strength of the final product.

[0122] Calcination conditions: From the starting calcination temperature to 600 °C, every 100 °C is taken as a temperature range for static calcination and the experiment of dropping 10 times from 1.6 meters. The heating and calcination time for each temperature range (100 °C) is 30 min; from 600 °C to the termination calcination temperature, it is taken as a temperature range (high - temperature range) for calcination. When the termination calcination temperature is 1100 °C, the heating time for the high - temperature range of 600 - 1100 °C is 2 h. When the termination calcination temperature is 1200 °C, the heating time for the high - temperature range of 600 - 1200 °C is 2.5 h. The comprehensive yield of each temperature range is tested and calculated, and the total comprehensive yield is calculated using the comprehensive yields of each temperature range.

[0123] For example, when the starting calcination temperature is 300 °C and the termination temperature is 1100 °C, the testing process is as follows: Starting from 300 °C, it is heated to 400 °C in 30 min, taken out for testing and calculating the comprehensive yield of the 300 - 400 °C range. The qualified materials after calcination and dropping in the 300 - 400 °C range are then heated from 400 °C to 500 °C in 30 min, taken out for testing and calculating the comprehensive yield of the 400 - 500 °C range. Then, the qualified materials after static calcination and dropping in the 400 - 500 °C range are heated from 500 °C to 600 °C in 30 min, taken out for testing and calculating the comprehensive yield of the 500 - 600 °C range. Finally, the qualified materials after static calcination and dropping in the 500 - 600 °C range are heated from 600 °C to 1100 °C in 2 h, taken out for testing the comprehensive yield of the 600 - 1100 °C range. Then, the total comprehensive yield of the entire 300 - 1100 °C temperature range is calculated according to the product of the comprehensive yields of each temperature range.

[0124] Taking the calcination starting temperature of 500°C and the termination temperature of 1200°C as an example, the test process is as follows: Taking 500°C as the starting temperature, it is heated to 600°C in 30 minutes, taken out for testing and calculating the comprehensive yield in the 500 - 600°C section. The qualified materials after calcination and falling in the 500 - 600°C section are then taken as the starting temperature of 600°C and heated to 1200°C in 2.5 hours, taken out for testing and calculating the comprehensive yield in the 600 - 1200°C section. Then, the total comprehensive yield in the entire temperature range of 500 - 1200°C is calculated based on the product of the comprehensive yields of each temperature section.

[0125] The test results are shown in Table 2.

[0126] Table 2

[0127]

[0128] As can be seen from the data in Table 2, the comprehensive yields of each temperature section in Examples 1 - 6 are all very high. Compared with the comparative examples, the total comprehensive yields are all significantly improved, indicating that the method of the present invention can significantly improve the strength of the granulated product after granulation. From the data of Comparative Example 2 and Comparative Example 3, it can be seen that without adding asphalt and furnace gas ash, the total comprehensive yield of the product is significantly reduced, indicating that the strength of the product is poor and it is easy to powder. From Comparative Example 1 and Comparative Example 5, it can be seen that when asphalt is not added, the comprehensive yield in the 400 - 500°C section is significantly reduced, indicating that asphalt plays an important role in improving the strength in the medium - low temperature section. At this temperature section, yellow dextrin has been completely carbonized and volatilized, and furnace gas ash has not yet sintered with the material. If asphalt is not added, the strength of the material in this temperature section will decrease. The reduction amplitude of the comprehensive yield in the 500 - 600°C section is relatively small because furnace gas ash has started to take effect when approaching 600°C. From the data of Comparative Example 4, it can be seen that without adding furnace gas ash, the comprehensive yield in the high - temperature section of 600°C - termination temperature is significantly reduced, indicating that furnace gas ash plays an important role in improving the strength in the high - temperature section.

[0129] 3. Testing of the pulverization rate at high temperature and high gas velocity

[0130] The products prepared in Examples 1 - 6 and Comparative Examples 1 - 5 are mixed at a mass ratio of 3:1 of the calcined granulated sample and petroleum coke. After purging with nitrogen at a flow rate of 2.5 NL / min for 30 minutes at 1050°C, the pulverization rate of the product is tested. The pulverization rate refers to the proportion of the mass of - 160 - mesh in the collected material plus the mass of the purge loss in the total mass. The results are shown in Table 3. The pulverization rate results indicate that the strengths of the granulated samples obtained after calcination are all very good.

[0131] Table 3

[0132] Example Powdering rate / % Example 1 2.77 Example 2 2.73 Example 3 2.71 Example 4 2.73 Example 5 2.60 Example 6 2.76 Comparative Example 1 2.77 Comparative Example 2 3.66 Comparative Example 3 3.43 Comparative Example 4 2.70 Comparative Example 5 2.78

[0133] 4. Chlorination experiment

[0134] Chlorination experiments were carried out on the granulated products in some embodiments. After calcination, the granulated samples and petroleum coke were mixed in a mass ratio of 3:1 and added into the chlorination device. The chlorination temperature was 1050 °C, the chlorine gas flow rate was 2.5 NL / min, and the ventilation time was 30 min. The chlorination rates of TiO2 and SiO2 were measured, and the results are shown in Table 4.

[0135] Table 4

[0136] Example <![CDATA[Chlorination rate of TiO2]]> <![CDATA[Chlorination rate of SiO2]]> Example 1 96.11％ 25.57％ Example 2 96.43％ 26.25％ Example 3 97.06％ 26.01％ Example 5 96.27％ 28.56％ Example 6 95.57％ 25.56％

[0137] 5. Explosion experiment

[0138] After spray granulation and drying according to the granulation conditions in Example 4, calcination was carried out in the temperature ranges of 400 - 500 °C, 500 - 600 °C, and 400 - 500 - 600 °C respectively. The heating-up time was set at 30 min / 100 °C. Among them, the calcination at 400 - 500 °C means taking out after starting from 400 °C as the initial calcination temperature and heating up to 500 °C in 30 min; the calcination at 500 - 600 °C means taking out after starting from 500 °C as the initial calcination temperature and heating up to 600 °C in 30 min; the calcination at 400 - 500 - 600 °C means taking out after starting from 400 °C as the initial calcination temperature and heating up to 600 °C in 60 min. The change in the particle size distribution of the material before and after calcination was observed. The purpose of this experiment was to investigate whether the material particles would explode when starting from 400 °C or 500 °C as the initial calcination temperature. The results are shown in Table 5.

[0139] Table 5

[0140]

[0141] It can be seen from the data in Table 5 that there is no obvious change in the particle size distribution of the material before and after calcination, indicating that the material particles will not explode during calcination in this temperature range.

[0142] Although the present invention has been illustrated and described with specific embodiments, it should be realized that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it; those of ordinary skill in the art should understand that: without departing from the spirit and scope of the present invention, the technical solutions described in the foregoing embodiments can be modified, or some or all of the technical features can be equivalently replaced; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention; therefore, this means that all such replacements and modifications within the scope of the present invention are included in the appended claims.

Claims

1. A granulation method for titanium-containing fine powder, characterized in that, It includes the following steps: Mix the titanium-containing fine powder with dextrin and then grind them. Then mix the ground material with asphalt, carry out spray granulation and the first screening, followed by drying and calcination, and perform the second screening on the calcined product to obtain it. Among them, the titanium-containing fine powder includes the first titanium-containing powder and furnace gas ash. The first titanium-containing powder includes sorted titanium concentrate and / or titanium slag fine powder. By mass percentage, the material with a particle size below 160 mesh in the titanium-containing fine powder accounts for ≥90%. The mass percentage of the furnace gas ash in the titanium-containing fine powder is 10%-30%. By mass percentage, the addition amount of the dextrin accounts for 2%-5% of the titanium-containing fine powder, and the addition amount of the asphalt accounts for 3%-5% of the titanium-containing fine powder.

2. The granulation method of titanium-containing fine powder according to claim 1, characterized in that, The first titanium-containing powder includes the sorted titanium concentrate and the titanium slag fine powder. The mass percentage of the sorted titanium concentrate in the titanium-containing fine powder is 30%-50%, and the mass percentage of the titanium slag fine powder in the titanium-containing fine powder is 30%-50%.

3. The granulation method of titanium-containing fine powder according to claim 1, characterized in that, It includes at least one of the following features (1) to (2): (1) The dextrin includes at least one of yellow dextrin, white dextrin, and British gum. (2) By mass percentage, the material with a particle size below 325 mesh in the ground material accounts for ≥95%.

4. The granulation method of titanium-containing fine powder according to claim 1, characterized in that, It includes at least one of the following features (1) to (2): (1) The particle size of the material entering the drying process after the first screening is 20-160 mesh. (2) After the first screening, the material smaller than 160 mesh is returned to the spray granulation process, and the material larger than 20 mesh is crushed. The material with a particle size of 20-160 mesh after crushing enters the drying process, and the material smaller than 160 mesh after crushing is returned to the spray granulation process.

5. The granulation method of titanium-containing fine powder according to claim 1, characterized in that, The temperature of the drying is 105-180 °C, and the time of the drying is 1-2 h.

6. The granulation method of titanium-containing fine powder according to claim 1, characterized in that It includes at least one of the following features (1) to (2): (1) The temperature of the calcination is 300-1300 °C, and the time of the calcination is 3-5 h. (2) The calcination is carried out in a rotary kiln.

7. The granulation method of titanium-containing fine powder according to claim 1, characterized in that It includes at least one of the following features (1) to (2): (1) The particle size of the product obtained after the second screening is 20-160 mesh. (2) After the second screening, the material larger than 20 mesh and smaller than 160 mesh is returned to the grinding process.

8. The granulation method of titanium-containing fine powder according to claim 1, characterized in that, It includes at least one of the following features (1) to (2): (1) The method of spray granulation is as follows: Place the mixture of the titanium-containing fine powder, dextrin, and asphalt in a granulation container. Under the rotating state of the granulation container, evenly spray a mist-like liquid onto the material, and the material forms balls after contacting the mist-like liquid to achieve granulation. (2) The spray granulation is carried out in a sugar coating machine.

9. The granulation method of titanium-containing fine powder according to claim 1, characterized in that It includes at least one of the following features (1) to (4): (1) The titanium grade of the titanium-containing fine powder is ≥75%. (2) The titanium grade of the sorted titanium concentrate is ≥86%, the mass percentage of calcium oxide is <0.13%, and the mass percentage of silicon dioxide is 3%-8%. (3) The titanium grade of the titanium slag fine powder is ≥81%, and the mass percentage of silicon dioxide is <3%. (4) The titanium grade of the furnace gas ash is ≥ 45%, the mass percentage of silicon dioxide is 8% - 13%, the mass percentage of aluminum oxide is 1.5% - 3%, and the mass percentage of manganese oxide is 3% - 6%.

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