Pretreatment method for sub-millimeter rutile powder granulation

Abstract

The invention discloses a pretreatment method for sub-millimeter rutile powder granulation, which comprises the following steps: (1) uniformly mixing sub-millimeter rutile powder and a binder to obtain a mixed raw material; (2) pretreating the mixed raw material by adopting one or a combination of more of high-pressure roller milling, wet milling and strong mixing, so that the raw material and the binder fully act and are tightly combined to obtain a pretreated raw material; (3) putting the pretreated raw materials into a granulator, and granulating; and (4) drying and curing the pelletized product to obtain the product. The invention provides a pretreatment method for sub-millimeter rutile powder granulation, which is suitable for all granulation processes at present. The submillimeter rutile powder is subjected to high-pressure roller grinding, wet grinding and strong mixing pretreatment, so that the use amount of a binder is reduced, and the granulation effect is improved. And the granulated product is uniform in particle size distribution and good in strength, and can be applied to a fluidizing chlorination furnace. The granulation method is high in qualified rate, and the granulation process is simple in procedure and environment-friendly.

Description

Technical Field

[0001] The invention belongs to the field of nonferrous metal metallurgy, and in particular relates to a pretreatment method for granulating submillimeter rutile powder. Background Art

[0002] The boiling chlorination method is the mainstream process for the production of titanium dioxide by the chlorination method in my country, with simple production equipment, large titanium tetrachloride output, and low three waste emissions. The boiling chlorination method requires that the calcium and magnesium impurity content of the raw materials entering the furnace is less than 1.5%, of which CaO is less than 0.14%, and the titanium grade is ≥90%. The boiling chlorination furnace is a fluidized bed system. In order to ensure that the titanium-rich material always maintains a fluidized state in the boiling chlorination furnace, the particle size distribution of the raw materials entering the furnace is required to be 100-900μm.

[0003] my country's titanium resources are mainly found in ilmenite, usually 40% to 45%. In order to make ilmenite meet the production requirements of boiling chlorination method, it needs to be enriched into high-grade titanium-rich materials (artificial rutile, high-titanium slag). Artificial rutile has advantages in product quality and performance structure, and plays an important role in high-end titanium products. my country's ilmenite contains a lot of calcium and magnesium impurities, which need to be removed by grinding and acid leaching to obtain artificial rutile, but the product particle size is basically less than 100μm. Therefore, domestic artificial rutile has the problem of too fine particles and is difficult to apply to boiling chlorination process. Submillimeter rutile powder has a small bulk density and fine particle size. In the natural stacking state, the particle spacing is large and there are few contact points. Some extremely fine particles show Brownian motion, and it is difficult to granulate submillimeter rutile powder in this state.

[0004] Currently, the granulation processes that can be applied to artificial rutile include: (1) disc granulation method. Patents US7931886, US4187117 and CN106319246, CN105271390B all use disc granulators to granulate fine-grained titanium-rich materials. The operation is simple and the process is mature. (2) V-type mixing granulation method. Patent EP0426731B1 uses white titanium as raw material and adopts V-type mixing granulator for granulation. (3) Fluidized bed granulation method. Chen et al. researchers use natural rutile concentrate as raw material and adopt FL-30 fluidized bed for granulation. This method mainly relies on the effect of binder and has high requirements on the amount and quality of binder. (4) High-speed stirring granulation method. Patent CN114702062B uses fine-grained titanium-rich materials as raw materials and adopts high-speed stirring granulation method for granulation. The operation is simple and the product particle size distribution is uniform. The above research objects are not submillimeter rutile powder (material with a particle size of less than 100 μm). After the above process is applied to submillimeter rutile powder (as shown in the comparative example), the granulation effect is not good and it is difficult to meet the boiling chlorination furnace charge requirements.

[0005] Therefore, it is urgent to propose a new pretreatment method for preparing boiling chlorination furnace charge, so that the submillimeter rutile powder has a better granulation effect, and the granulated product has higher cold strength and thermal stability, which is of great significance to the full utilization of titanium resources and the development of high-end titanium product production in my country. Summary of the invention

[0006] In view of the problem that submillimeter rutile powder in the prior art is difficult to meet the requirements of the boiling chlorination process, the purpose of the present invention is to provide a pretreatment method for submillimeter rutile powder granulation, which has the characteristics of simple process, high efficiency, high product quality and low cost, and can meet the requirements of the boiling chlorination process.

[0007] In order to achieve the above object, the present invention provides the following solutions:

[0008] The present invention provides a pretreatment method for submillimeter rutile powder granulation, comprising the following steps:

[0009] (1) mixing submillimeter rutile powder and a binder uniformly to obtain a mixed raw material;

[0010] (2) pre-treating the mixed raw materials, wherein the pre-treating adopts one or more combinations of high-pressure roller grinding, wet grinding and strong mixing, so that the raw materials and the binder can fully interact and tightly combine to obtain pre-treated raw materials;

[0011] (3) placing the pretreated raw material in a granulator for granulation;

[0012] (4) Drying and solidifying the granulated product to obtain the product.

[0013] In a preferred embodiment, in step (1), the submillimeter rutile powder is a material having a particle size of less than 100 μm after chemical treatment.

[0014] In a preferred embodiment, in step (1), the amount of the binder added is 0.5% to 3% of the mass of the submillimeter rutile powder, and the binder is any binder currently available for artificial rutile granulation.

[0015] In a preferred embodiment, in step (2), the bulk density of the sub-millimeter rutile powder is increased to 1.00 g / cm by high pressure roller milling. 3 above.

[0016] In a preferred embodiment, in step (2), the moisture content during grinding is 4% to 8%, and the grinding time is 2 to 10 minutes.

[0017] In a preferred embodiment, in step (2), during the vigorous mixing process, the stirring speed is 1000 to 4000 rpm and the stirring time is 2 to 10 min.

[0018] In a preferred embodiment, in step (3), the granulation method is selected from any one of a fluidized bed granulation method, a disc granulation method, a V-type mixer granulation method, and a high-speed stirring granulation method.

[0019] In a preferred embodiment, in step (4), the granulated product particles are placed in a fluidized bed dryer for drying, and the fine particles carried out by the airflow during the drying process and the coarse particles that settle down are collected and returned to the ingredients in step (1).

[0020] In a preferred embodiment, in step (4), the material stabilized in the fluidized bed is dried to obtain a qualified product, and the qualified particle size is 100 to 900 μm.

[0021] Since the sub-millimeter rutile powder particles less than 100μm are too small, the relative force between the particles is large, which can easily lead to the agglomeration of material particles during the boiling chlorination process, forming channeling and slugging phenomena, resulting in insufficient contact between the titanium-rich material and chlorine in the furnace, reducing the chlorination reaction rate, and causing large particle escape, high dust collection pressure of the boiling chlorination furnace, a large proportion of mud in the titanium tetrachloride product, and increased slag production. Therefore, it is necessary to prepare it into particles that meet the particle size requirements of the boiling chlorination furnace through a granulation process.

[0022] The pretreatment method (high-pressure roller milling, wet grinding, and strong mixing) adopted in the present invention can effectively improve the granulation efficiency of submillimeter rutile powder. The high-pressure roller milling process increases the specific surface area of ​​submillimeter rutile powder particles through the roller extrusion effect, so that particles and particles, particles and binders are closely combined, and the bulk density of submillimeter rutile powder particles is increased; wet grinding promotes the action between the binder and the submillimeter rutile powder through the collision between the iron ball and the rubber wall in the wet grinding barrel, which can effectively reduce the amount of binder; strong mixing makes the binder fully distributed in the submillimeter rutile powder, so that the particle size distribution of the granulated product is more uniform, and the proportion of large particles and fine particles in the granulated product is reduced.

[0023] Compared with the prior art, the beneficial technical effects of the present invention are:

[0024] 1) The present invention provides a pretreatment method for granulating submillimeter rutile powder, which is applicable to all current granulation processes. By pre-treating the submillimeter rutile powder by high-pressure roller grinding, moist grinding, and strong mixing, the amount of binder is reduced and the granulation effect is improved. The granulated product has a uniform particle size distribution and good strength, and can be used in a boiling chlorination furnace. This granulation method has a high pass rate, a simple granulation process, and is environmentally friendly.

[0025] 2) Patent CN 114702061 B and Patent CN 114702062 B select ferrous sulfate, aluminum sulfate, and silica sol as binders to granulate fine-grained titanium-rich materials, and the granulation processes include disc granulator, fluidized bed granulator, V-type mixing granulator, spray drying granulator, and high-speed stirring granulator. Fine-grained titanium-rich materials include fine-grained high-titanium slag, fine-grained artificial rutile, and natural rutile. Among them, the surface properties of high-titanium slag are active and easier to bond with the binder to form a mass. The properties of artificial rutile are more stable and the difficulty of granulation is higher. There is a difference in the difficulty of granulation between the two. When the granulation method in the above patents is used to granulate submillimeter rutile powder, the granulation product with a particle size distribution of 100 to 900 μm accounts for only 46.78%, which is much lower than the granulation method proposed in this patent. DETAILED DESCRIPTION

[0026] The technical solutions in the embodiments of the present invention will be described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0027] The present invention provides a pretreatment method for granulating submillimeter rutile powder, wherein a binder solution is prepared by mixing a binder with water, and the prepared binder solution is sprayed on artificial rutile particles smaller than 100 μm and mixed evenly. The mixed material is pretreated and then placed in a granulator for granulation, and the product particles obtained by granulation are dried in a fluidized bed. The cold strength and hot strength of particles with a particle size distribution between 100 and 900 μm are measured.

[0028] In the present invention, the cold strength and hot strength of the granulated product are tested. The heat treatment method of the product particles is carried out in a muffle furnace by a coke burying method. 200g of dry granular products with a particle size distribution of 100-900μm are weighed each time, placed in a Φ10×13cm graphite crucible and wrapped with coke powder (particle size greater than 3mm, washed until there is no micropowder particles on the surface and completely dried), placed in a muffle furnace, heated to 1000°C with the furnace, and taken out after 60 minutes for measuring its hot strength.

[0029] The present invention adopts the method of measuring the wear index of the granulated product as the cold and hot strength characterization method of the granulated product. The present invention adopts the reduction pulverization drum to detect the wear index of the product granules, the drum size is Φ130×200mm, the speed is 30 rpm, and the time is 10 minutes. Each time, 100g of granular materials distributed in 100-900μm are weighed for the experiment, and the arithmetic mean value is taken as the wear index RDI after repeating 3 times.

[0030]

[0031] Where: m D0 —The mass of the sample before drum rotation;

[0032] m D1 —Mass after drumming +0.1mm.

[0033] The process of the present invention is described below in conjunction with specific examples. Table 1 shows the basic properties of the submillimeter rutile powder used in the examples.

[0034] Table 1 Basic properties of submillimeter rutile powder

[0035]

[0036] Example 1

[0037] Weigh 20g of ferrous sulfate and put it into 100g of water to prepare a binder solution for later use. Weigh 1000g of submillimeter rutile powder and mix it evenly with the binder. After pretreatment with a high-pressure roller mill, the bulk density of the rutile powder is increased to 1.21g / cm 3 , placed in a high-speed stirring granulator, set the stirring paddle speed to 400rpm, the cutting knife speed to 1000rpm, and the granulation time to 6 minutes. The granulated product particles are placed in a fluidized bed dryer for drying, and the particle size distribution of the particles is between 100 and 900μm, accounting for 75.69%. The unqualified particles are returned to the ingredients. After secondary granulation, the particle size distribution of the particles is between 100 and 900μm, accounting for 94.58%. The cold strength wear index of the particles is 2.36%, and the hot strength wear index of the particles is 1.48%.

[0038] Example 2

[0039] Weigh 30g of aluminum sulfate and put it into 100g of water to prepare a binder solution for standby use. Weigh 1000g of submillimeter rutile powder and mix it evenly with the binder. After pre-grinding, the moisture content is 6%, the grinding time is 4min, and it is placed in a disc granulator. The disc speed is set to 20r / min and the granulation time is 2min. The granulated product particles are placed in a fluidized bed dryer for drying, and the particle size distribution is between 100 and 900μm, accounting for 75.35%, the particle cold strength wear index is 11.46%, and the particle hot strength wear index is 5.04%.

[0040] Example 3

[0041] Weigh 20g of silica sol and put it into 200g of water to prepare a binder solution for later use. Weigh 1000g of sub-millimeter rutile powder and mix it evenly with the binder. After pretreatment with a high-pressure roller mill, the bulk density of the rutile powder is increased to 1.13g / cm 3, placed in a V-type mixing granulator, set the stirring rod speed to 1500-3000r / min, the granulation time to 300s, and the product after fluidized bed drying has a particle size distribution between 100 and 900μm, accounting for 77.96%, the particle cold strength wear index is 8.63%, and the particle hot strength wear index is 4.33%.

[0042] Example 4

[0043] Weigh 20g of silica sol and put it into 200g of water to prepare a binder solution for later use. Weigh 1000g of submillimeter rutile powder and mix it evenly with the binder. After pretreatment with a high-pressure roller mill, the bulk density of the rutile powder is increased to 1.16g / cm 3 , put into the fluidized bed granulation device, the fluidization speed is 0.23m / s, and the material filling rate is 0.9%. Another 10g silica sol is weighed and put into 200g water to prepare a binder solution and sprayed into the atomizer of the fluidized bed granulator. The dispersed binder liquid is distributed to the surface of the material, mixed and condensed into particles under the action of pneumatics. The atomization pressure is 0.2MPa and the spraying time is 60min. After fluidized air drying, the product has a particle size distribution between 100 and 900μm, accounting for 79.23%, the particle cold strength wear index is 12.36%, and the particle hot strength wear index is 7.65%.

[0044] Example 5

[0045] Weigh 20g of ferrous sulfate and put it into 100g of water to prepare a binder solution for standby use. Weigh 1000g of submillimeter rutile powder and the binder and mix them evenly in a strong mixer, with a stirring speed of 3000rpm and a stirring time of 5min; place the raw materials after strong mixing pretreatment in a high-speed stirring granulator, set the stirring paddle speed to 400rpm, the cutting knife speed to 1000rpm, and the granulation time to 6 minutes. The granulated product particles are placed in a fluidized bed dryer for drying, and the particle size distribution is between 100 and 900μm, accounting for 79.63%. Return the unqualified particles to the batching. After secondary granulation, the particle size distribution is between 100 and 900μm, accounting for 96.33%. The cold strength wear index of the particles is 10.23%, and the hot strength wear index of the particles is 5.31%.

[0046] Example 6

[0047] Weigh 20g of ferrous sulfate and put it into 100g of water to prepare a binder solution for later use. Weigh 1000g of submillimeter rutile powder and mix it evenly with the binder. After pretreatment with a high-pressure roller mill, the bulk density of the rutile powder is increased to 1.20g / cm 3; Then continue the grinding treatment, the grinding moisture is 6%, and the grinding time is 4 minutes; the pretreated raw materials are placed in a high-speed stirring granulator, the stirring paddle speed is set to 400rpm, the cutting knife speed is set to 1000rpm, and the granulation time is 6 minutes. The granulated product particles are placed in a fluidized bed dryer for drying, and the particle size distribution of the obtained particles is between 100 and 900μm, accounting for 76.32%. The unqualified particles are returned to the ingredients. After secondary granulation, the particle size distribution of the obtained particles is between 100 and 900μm, accounting for 93.26%. The cold strength wear index of the particles is 12.69%, and the hot strength wear index of the particles is 6.14%.

[0048] Example 7

[0049] Weigh 20g of ferrous sulfate and put it into 100g of water to prepare a binder solution for standby use. Weigh 1000g of submillimeter rutile powder and binder for strong mixing pretreatment, stirring speed is 3000rpm, stirring time is 5min; put the mixed raw materials into a grinding mill, grinding water is 6%, grinding time is 4min; finally, the raw materials are pretreated by high-pressure roller milling, and the bulk density of rutile powder is increased to 1.05g / cm by high-pressure roller milling. 3 . The pretreated raw materials were placed in a high-speed stirring granulator, the stirring paddle speed was set to 400rpm, the cutting knife speed was set to 1000rpm, and the granulation time was 6 minutes. The granulated product particles were placed in a fluidized bed dryer for drying, and the particle size distribution of the particles was between 100 and 900μm, accounting for 82.13%. The unqualified particles were returned to the batching. After secondary granulation, the particle size distribution of the particles was between 100 and 900μm, accounting for 96.93%. The cold strength wear index of the particles was 6.12%, and the hot strength wear index of the particles was 2.33%.

[0050] Comparative Example 1

[0051] Weigh 30g of ferrous sulfate and put it into 200g of water to prepare a binder solution for standby use. Weigh 1000g of submillimeter rutile powder and mix it evenly with the binder, place it in a wet high-speed stirring granulator, set the stirring paddle speed to 400rpm, the cutting knife speed to 1000rpm, and the granulation time to 6 minutes. The granulated product particles are placed in a fluidized bed dryer for drying, and the particle size distribution is between 100 and 900μm, accounting for 46.35%. Using ferrous sulfate as a granulation binder, the granulation efficiency of submillimeter rutile powder is poor.

[0052] Comparative Example 2

[0053] Weigh 30g of silica sol and put it into 200g of water to prepare a binder solution for standby use. Weigh 1000g of fine-grained artificial rutile and mix it evenly with the binder, place it in a wet high-speed stirring granulator, set the stirring paddle speed to 400rpm, the cutting knife speed to 1000rpm, and the granulation time to 6min. The granulated product particles are placed in a fluidized bed dryer for drying, and the particle size distribution obtained is between 100 and 900μm, accounting for 32.96%. The granulation efficiency of submillimeter rutile powder is poor.

[0054] Comparative Example 3

[0055] Weigh 30g of aluminum sulfate and put it into 200g of water to prepare a binder solution for standby use. Weigh 1000g of fine-grained artificial rutile and mix it evenly with the binder, place it in a wet high-speed stirring granulator, set the stirring paddle speed to 400rpm, the cutting knife speed to 1000rpm, and the granulation time to 6min. The granulated product particles are placed in a fluidized bed dryer for drying, and the particle size distribution obtained is between 100 and 900μm, accounting for 46.78%. The granulation efficiency of submillimeter rutile powder is poor.

[0056] Comparative Example 4

[0057] Weigh 30g of aluminum sulfate and put it into 100g of water to prepare a binder solution for standby use. Weigh 1000g of fine-grained artificial rutile and mix it evenly with the binder and place it in a disc granulator at a speed of 20r / min and a granulation time of 2min. Add 100g of water during the disc granulation process. The granulated product particles are placed in a fluidized bed dryer for drying, and the particle size distribution obtained is between 100 and 900μm, accounting for 42.96%. The granulation efficiency of submillimeter rutile powder is poor.

[0058] Comparative Example 5

[0059] Weigh 30g of aluminum sulfate and put it into 400g of water to prepare a binder solution for standby use. Weigh 1000g of fine-grained artificial rutile and place it in a fluidized bed granulator with a fluidization speed of 0.23m / s and a material filling rate of 0.9%. Spray the prepared binder solution through the atomizer of the fluidized bed granulator, and the dispersed binder liquid is distributed to the surface of the material, mixed and condensed into particles under the action of pneumatics. The atomization pressure is 0.2MPa and the spraying time is 60min. After fluidized air drying, the granulated product particles have a particle size distribution between 100 and 900μm, accounting for 34.56%. The granulation efficiency of submillimeter rutile powder is poor.

[0060] Comparative Example 6

[0061] Weigh 30g of aluminum sulfate and put it into 100g of water to prepare a binder solution for standby use. Weigh 1000g of fine-grained artificial rutile and place it in a V-type mixing granulator. Add the binder solution at a speed of 40r / min through the built-in stirring system of the mixer. After sufficient mixing, set the stirring rod speed to 1500-3000r / min, the granulation time to 300s, and place the granulated product particles in a fluidized bed dryer for drying. The particle size distribution of the obtained particles is between 100 and 900μm, accounting for 33.68%. The granulation efficiency of submillimeter rutile powder is poor.

[0062] The present invention provides a sub-millimeter rutile powder granulation method, which is applicable to various granulation binders and granulation processes, can effectively improve the granulation effect, and the granulated product has high strength and is easy to store and transport. It effectively solves the problem that sub-millimeter rutile powder is difficult to be used in a boiling chlorination furnace to prepare titanium tetrachloride due to its too fine particles.

[0063] The above is only a preferred embodiment of the present invention, and the protection scope of the present invention is not limited to the above embodiments. For those skilled in the art, improvements and changes obtained without departing from the technical concept of the present invention should also be regarded as the protection scope of the present invention.

Claims

1. A pretreatment method for submillimeter rutile powder granulation, characterized in that: The following steps are involved: (1) mixing submillimeter rutile powder and a binder uniformly to obtain a mixed raw material; (2) pre-treating the mixed raw materials, wherein the pre-treating adopts one or more combinations of high-pressure roller grinding, wet grinding and strong mixing, so that the raw materials and the binder can fully interact and tightly combine to obtain pre-treated raw materials; (3) placing the pretreated raw material in a granulator for granulation; (4) Drying and solidifying the granulated product to obtain the product.

2. A pretreatment method for submillimeter rutile powder granulation according to claim 1, characterized in that: In step (1), the submillimeter rutile powder is a material with a particle size less than 100 μm after chemical treatment; and the amount of binder added is 0.5% to 3% of the mass of the submillimeter rutile powder.

3. A pretreatment method for submillimeter rutile powder granulation according to claim 1, characterized in that: In step (2), the bulk density of sub-millimeter rutile powder is increased to 1.00 g / cm by high pressure roller milling. 3 above.

4. A pretreatment method for submillimeter rutile powder granulation according to claim 1, characterized in that: In step (2), the moisture content during grinding is 4% to 8%, and the grinding time is 2 to 10 minutes.

5. A pretreatment method for submillimeter rutile powder granulation according to claim 1, characterized in that: In step (2), during the vigorous mixing process, the stirring speed is 1000 to 4000 rpm and the stirring time is 2 to 10 minutes.

6. A pretreatment method for submillimeter rutile powder granulation according to claim 1, characterized in that: In step (3), the granulation method is selected from any one of fluidized bed granulation, disk granulation, V-type mixer granulation, and high-speed stirring granulation.

7. A pretreatment method for submillimeter rutile powder granulation according to claim 1, characterized in that: In step (4), the granulated product particles are placed in a fluidized bed dryer for drying. The fine particles carried out by the airflow during the drying process and the coarse particles that settle down are collected and returned to the ingredients in step (1).

8. A pretreatment method for submillimeter rutile powder granulation according to claim 1, characterized in that: In step (4), the material stabilized in the fluidized bed is dried to obtain a qualified product, and the qualified particle size is 100 to 900 μm.

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