阅读说明：本技术 一种莫来石质铸造型砂的生产工艺 (Production process of mullite foundry sand ) 是由 张德强 陈伟雄 刘明红 于 2021-09-23 设计创作，主要内容包括：本发明公开了一种莫来石质铸造型砂的生产工艺,属于铸造型砂生产工艺技术领域,包括以下步骤：将各种不同品位的铝矾土矿分别单独破碎,经筛分、烘干放入磨头仓待用；测量磨头仓中各原料的成分,然后用计量皮带秤按比例下料,喂入干法球磨机中进行粉磨,经高效选粉机得到合格生料粉；收集,并进行制浆,制浆时,干粉量及水量通过计算机来控制,制成得到的泥浆；放入泥浆池中储存困料,再抽入高位罐,然后再进行造粒得到球形生料；进行高温煅烧,得到莫来石质铸造型砂,再经冷却,输送至成品库得到成品。该工艺可以生产各种粒度的球形度好的半生料,也就是说粒度可以人为的控制,而且在输送过程中把熟料中的表面打磨光滑,从而提高了成品的品质。(The invention discloses a production process of mullite foundry molding sand, which belongs to the technical field of foundry molding sand production processes and comprises the following steps: respectively and independently crushing bauxite ores of different grades, screening, drying and putting into a grinding head bin for later use; measuring the components of the raw materials in the grinding head bin, then feeding the raw materials in proportion by using a measuring belt scale, feeding the raw materials into a dry-process ball mill for grinding, and obtaining qualified raw material powder by using a high-efficiency powder concentrator; collecting and pulping, wherein the amount of dry powder and the amount of water are controlled by a computer during pulping to prepare the obtained slurry; putting the mixture into a slurry pool to store ageing materials, pumping the ageing materials into a high-level tank, and then granulating to obtain spherical raw materials; and (4) carrying out high-temperature calcination to obtain mullite foundry molding sand, cooling, and conveying to a finished product warehouse to obtain a finished product. The process can produce semi-raw material with various particle sizes and good sphericity, i.e. the particle size can be controlled artificially, and the surface of the clinker is polished smoothly in the conveying process, thereby improving the quality of finished products.)

1. The production process of the mullite foundry sand is characterized by comprising the following steps of:

a) respectively and independently crushing bauxite ores of different grades, screening, drying and putting into a grinding head bin for later use;

b) measuring the components of the raw materials in the grinding head bin, then feeding the raw materials in proportion by using a measuring belt scale, feeding the raw materials into a dry-process ball mill for grinding, obtaining qualified raw material powder by using a high-efficiency powder concentrator, and controlling the particle size of the qualified raw material powder by adjusting the rotating speed;

c) collecting the obtained qualified raw meal powder by a bag dust collector, and pulping in a dry powder pulping machine, wherein the amount of the dry powder and the water amount are controlled by a computer during pulping, and the moisture content of the prepared mud is 40-60%;

d) putting the obtained slurry into a slurry pool to store the ageing materials, pumping the ageing materials into a high-level tank by using a plunger pump, and pumping the ageing materials into a spray gun of a spray tower by using the plunger pump to granulate so as to obtain spherical raw materials;

e) and (3) feeding the obtained spherical raw material into a rotary kiln for high-temperature calcination to obtain mullite foundry molding sand, cooling by a single-cylinder cooler, and conveying to a finished product warehouse by a pneumatic conveying device to obtain a finished product.

2. The process for producing mullite foundry sand according to claim 1, wherein the bauxite ores of different grades in the step a are bauxite ores having an aluminum content of 40%, 45%, 55%, 60%.

3. The process for producing mullite foundry sand according to claim 1, wherein the screened grain size in step a is 1-5 mm.

4. The process for producing mullite foundry sand according to claim 1, wherein the drying in step a is carried out to a moisture content of 0.5-1.0%.

5. The process for producing the mullite foundry sand of claim 1, wherein the qualified raw material powder in the step b has a particle size of 30 to 50 μm and is more than 90%.

6. The process for producing the mullite foundry sand of claim 1, wherein the aging time in the step d is 16 to 48 hours.

7. The process for producing the mullite foundry sand according to claim 1, wherein in the step d, different spray gun spray piece diameters, swirl piece thicknesses and plunger pump pressures are selected according to the granularity requirements of the finished product, wherein the spray piece diameters are 2.0-6mm, the swirl piece thicknesses are 4-8mm, and the plunger pump pressures are 1.0-2.0 MPa.

8. The process for producing mullite foundry sand according to claim 1, wherein the green spherical material obtained in step d has a water content of 0.5-3.0% and a particle size of 0.075-1.0 mm.

9. The process for producing mullite foundry sand as claimed in claim 1, wherein the calcination temperature in step e is controlled at 1400 ℃ and 1700 ℃ for 2-4 h.

10. The process for producing the mullite foundry sand as claimed in claim 1, wherein the clinker temperature in step e is 1100-1300 ℃ and the clinker is cooled to 40-90 ℃.

Technical Field

The invention belongs to the technical field of casting molding sand production processes, and particularly relates to a production process of mullite casting molding sand.

Background

The mullite foundry sand is high-quality spherical foundry sand, has the characteristics of smooth surface, high aluminum, low iron, high mullite phase, high refractoriness, low expansion coefficient, reusability, environmental protection, safety and the like, and the shell manufactured by the mullite foundry sand has the characteristics of high strength, high temperature resistance, easy shelling, no deformation, accurate size, smooth surface, high yield and the like, can replace imported zircon sand with high price, and reduces the production cost of a foundry enterprise.

At present, mullite foundry sand produced by other manufacturers in China is generally produced by two production processes, one is light-burned high-grade bauxite, the high-temperature melting is carried out by an electric furnace, and then the high-temperature melting is carried out by compressed air for blowing and granulating, the production method has high requirements on the aluminum content in the raw materials, the aluminum content in the finished product is 65-82%, low-temperature light burning is needed firstly, impurities and water in minerals are burnt, meanwhile, the raw materials are melted by an electric melting mode, the temperature is up to 2000 ℃, the compressed air for blowing and granulating is adopted after the raw materials are melted, and the particle size is difficult to control. In conclusion, the process requires high grade of aluminum in the raw materials, and needs to be lightly fired in advance, so the source of the raw materials is limited, the raw materials are melted at high temperature, the compressed air is blown into particles, the required power consumption is high, the particle size is not easy to control, and in addition, the product bulk density of the process is high and reaches 1.9-2.0g/cm³For the same casting pattern, a larger amount of molding sand is required. The other is wet grinding, drying, balling with ball forming mill, stoving and calcining in rotary kiln, and this process has long grinding time, low yield, no fine grinding and no controlled granularity distribution of raw material, so that the sintered clinker has low bulk density of 1.40-1.60g/cm³The pelletizing equipment of the process is a pelletizer, the pelletizer cannot produce finished products with fine granularity, the pelletizer considers the requirement of the product sphericity, the yield of a single pelletizer is low, and a plurality of pelletizing equipment are needed on a production line to meet the requirement of the yield, so the occupied area is large, and the production line is inconvenient to manage.

Disclosure of Invention

Aiming at the problems in the prior art, the invention aims to provide a production process of mullite foundry sand, which can produce semi-raw materials with various particle sizes and good sphericity, namely, the particle size can be artificially controlled, and the surface of clinker is polished smoothly in the conveying process, so that the quality of finished products is improved.

In order to realize the purpose, the invention adopts the technical scheme that:

a production process of mullite foundry sand comprises the following steps:

a) respectively and independently crushing bauxite ores of different grades, screening, drying and putting into a grinding head bin for later use;

b) measuring the components of raw materials in a grinding head bin, specifically measuring the content of aluminum and iron in each bin, obtaining the required raw material ratio by calculation according to the requirement of the content of aluminum and iron in a finished product, then feeding the raw material in proportion by using a measuring belt scale, feeding the raw material into a dry ball mill for grinding, obtaining qualified raw material powder by using a high-efficiency powder concentrator, and controlling the particle size of the qualified raw material powder by adjusting the rotating speed (different raw material powder fineness corresponds to the rotating speed of different powder concentrators, which is to adjust the rotating speed of the powder concentrator by detecting the raw material powder fineness);

c) collecting the obtained qualified raw meal powder by a bag dust collector, and pulping in a dry powder pulping machine, wherein the amount of the dry powder and the water amount are controlled by a computer during pulping, and the moisture content of the prepared mud is 40-60%;

d) putting the obtained slurry into a slurry pool to store the ageing materials, pumping the ageing materials into a high-level tank by using a plunger pump, and pumping the ageing materials into a spray gun of a spray tower by using the plunger pump to granulate so as to obtain spherical raw materials;

e) and (3) feeding the obtained spherical raw material into a rotary kiln for high-temperature calcination to obtain mullite foundry molding sand, cooling by a single-cylinder cooler, and conveying to a finished product warehouse by a pneumatic conveying device to obtain a finished product.

Further, the bauxite ores of different grades in the step a refer to bauxite ores with aluminum contents of 40%, 45%, 55% and 60%.

And furthermore, before the measurement in the step b, the same ore raw material is stirred and mixed uniformly in the same warehouse, and then sampling measurement is carried out.

Furthermore, the particle size of the sieved particles in the step a is 1-5 mm.

Further, drying in the step a until the moisture content is 0.5-1.0%.

Further, the qualified raw material powder in the step b has the particle size of 30-50 microns and reaches more than 90%.

Further, the ageing time in the step d is 16-48 h.

And further, in the step d, according to the granularity requirement of a finished product, selecting different spray guns to spray the diameter of the spinning disk, the thickness of the spinning disk and the pressure of the plunger pump, wherein the diameter of the spraying disk is 2.0-6mm, the thickness of the spinning disk is 4-8mm, and the pressure of the plunger pump is 1.0-2.0 MPa.

Furthermore, the water content of the spherical raw material obtained in the step d is 0.5-3.0%, and the particle size is 0.075-1.0 mm.

Furthermore, the calcination temperature in the step e is controlled at 1400 ℃ and 1700 ℃ for 2-4 h.

Further, the temperature of the clinker discharged from the kiln in the step e is 1100-1300 ℃, and the clinker is cooled to 40-90 ℃.

Furthermore, the obtained finished product can be prepared into various types of finished products through screening, blending and mixing.

The invention has the beneficial effects that: (1) the raw materials are crushed, dried, warehoused, stirred and mixed, then sampled, the aluminum content is different due to the enrichment of minerals and the sampling in different places in the same batch of minerals, the crushed raw materials are mixed in the same warehouse, the samples are more uniform, the samples are more representative, the components are more real, and then the raw materials are discharged in proportion by using a metering belt scale, so that the components of the prepared raw materials are stable and uniform; the dry grinding is adopted and the high-efficiency powder concentrator is used for sorting, the dry grinding can be continuously produced and finely ground, the improvement of the bulk density of finished products is facilitated, the particle size distribution of the raw material powder can be controlled by the rotating speed, the air quantity and the like of the high-efficiency powder concentrator, the control is convenient, and the conversion of different varieties is facilitated; the dry powder pulping process is continuously carried out on a production line, the water content of the slurry is controlled by an automatic metering sensor, the water weight is firstly metered by a water flow meter, the weight of the raw material is metered by a weighing sensor, and finally the control is carried out by a computer, so that the control of the water content of the slurry is convenient and accurate;

(2) in the process of storing the ageing mixture by putting the slurry into the slurry tank, the powder and the moisture are fully mixed and wetted, so that the surface of a finished product is smooth, and simultaneously, the slurries in the tanks are mixed with each other during ageing, so that the components are more uniform; the raw material is dried by a spray tower, one device can complete two functions, namely drying and granulating, the obtained raw material has good sphericity, the particle size distribution can be controlled by the water content of slurry, the diameter of a spray sheet, the thickness of a vortex sheet, the pressure of the slurry and the like, and the particle size of the product can be adjusted and controlled;

(3) the temperature is proper when the rotary kiln is used for calcination, the temperature is 1400-1700 ℃, and the retention time of the clinker in the rotary kiln is also adjusted within the range of 2-4h through a frequency converter of a rotary kiln motor; the cooled clinker is conveyed by a pneumatic conveying device, and the clinker is continuously collided and rubbed with the pipe wall in a conveying pipeline, is polished to be smooth and has a shaping effect, so that the product has better sphericity and smoother surface; the whole production line is controlled by a DCS (distributed control system), so that the automation degree is high and the management is convenient; the bulk density of the final product is 1.59-1.75g/em³The porosity is low and the bulk density is appropriate.

Drawings

FIG. 1 is a schematic view of a production process of the present invention;

FIG. 2 is a pictorial view of foundry sand produced in accordance with the present invention;

FIG. 3 is an enlarged representation of foundry sand produced in accordance with the present invention.

Detailed Description

For a better understanding of the present invention, embodiments of the present invention are described in detail below with reference to examples, but those skilled in the art will understand that the following examples are only for illustrating the present invention and should not be construed as limiting the scope of the present invention.

The specific calculation method of the raw material ratio in step b of this embodiment is as follows: for example, one ore a has an aluminum content of 40% and the other ore B has an aluminum content of 55%, and to obtain a final product with an aluminum content of 60%, the loss on ignition of the raw meal is 15%, the ratio is 40% a/(1-15%) + 55% B/(1-15%) -60%, and at the same time, a + B-100%, calculated as a-27% and B-73%.

Example 1:

a production process of mullite foundry sand comprises the following steps:

a) respectively and independently crushing various bauxite ores of different grades, screening to prepare bauxite ores with the grain diameter of 3-5mm, drying until the moisture content is 0.5%, and putting the bauxite ores into a grinding head bin for later use, wherein the bauxite ores of different grades refer to bauxite ores with the aluminum content of 40% and 55%;

b) measuring the components of the raw materials in the grinding head bin, and then weighing the raw materials by a weighing belt scale in a ratio of 27: 73, feeding the materials into a dry ball mill for grinding, and obtaining qualified raw material powder by a high-efficiency powder concentrator, wherein the particle size of the qualified raw material powder is controlled by adjusting the rotating speed, and the qualified raw material powder has the particle size of 30-50 mu m and reaches more than 90 percent;

c) collecting the obtained qualified raw meal powder by a bag dust collector, and pulping in a dry powder pulping machine, wherein the dry powder amount and the water amount are controlled by a computer during pulping, and the moisture content of the prepared mud is 40%;

d) putting the obtained slurry into a slurry pool to store ageing materials for 16h, pumping the ageing materials into a high-level tank by using a plunger pump, pumping the ageing materials into a spray gun of a spray tower by using the plunger pump to granulate to obtain spherical raw materials, wherein the water content of the spherical raw materials is 3.0%, the particle size of the spherical raw materials is 0.075-0.09mm, and different spray gun spray piece diameters, cyclone piece thicknesses and plunger pump pressures are selected according to the granularity requirements of finished products, wherein the spray piece diameter is 2.0mm, the cyclone piece thickness is 5mm, and the plunger pump pressure is 1.0 MPa;

e) and (3) feeding the obtained spherical raw material into a rotary kiln for high-temperature calcination, controlling the calcination temperature at 1550 ℃ for 3 hours to obtain mullite foundry molding sand, taking the clinker out of the kiln at 1100 ℃, cooling the clinker to 60 ℃ by a single-cylinder cooler, and conveying the clinker to a finished product warehouse by a pneumatic conveying device to obtain a finished product with the aluminum content of 60%.

Example 2:

a production process of mullite foundry sand comprises the following steps:

a) respectively and independently crushing various bauxite ores of different grades, screening to prepare bauxite ores with the grain diameter of 1-4mm, drying until the moisture content is 1.0%, and putting the bauxite ores into a grinding head bin for later use, wherein the bauxite ores of different grades refer to bauxite ores with the aluminum content of 45% and 60%;

b) measuring the components of each raw material in a grinding head bin, then feeding the raw materials by using a metering belt scale according to the proportion of 3: 2, feeding the raw materials into a dry-process ball mill for grinding, and obtaining qualified raw material powder by using a high-efficiency powder concentrator, wherein the particle size of the qualified raw material powder is controlled by adjusting the rotating speed, and the particle size of the qualified raw material powder is 30-50 mu m and reaches more than 90%;

c) collecting the obtained qualified raw meal powder by using a bag dust collector, and pulping the raw meal powder in a dry powder pulping machine, wherein the dry powder amount and the water amount are controlled by a computer during pulping, and the moisture content of the prepared mud is 60%;

d) putting the obtained slurry into a slurry pool for storage and ageing for 48 hours, pumping the slurry into a high-level tank by using a plunger pump, pumping the slurry into a spray gun of a spray tower by using the plunger pump for granulation to obtain spherical raw material, wherein the water content of the spherical raw material is 0.5%, the particle size of the spherical raw material is 0.08-1.0mm, and according to the granularity requirement of a finished product, selecting different spray gun spray piece diameters, cyclone piece thicknesses and plunger pump pressures, wherein the spray piece diameter is 6mm, the cyclone piece thickness is 8mm, and the plunger pump pressure is 2.0 MPa;

e) and (3) feeding the obtained spherical raw material into a rotary kiln for high-temperature calcination, controlling the calcination temperature at 1400 ℃ for 4 hours to obtain mullite foundry molding sand, cooling the clinker discharged from the kiln to 40 ℃ by a single-cylinder cooler, and conveying the clinker to a finished product warehouse by a pneumatic conveying device to obtain a finished product with the aluminum content of 60%.

Example 3:

a production process of mullite foundry sand comprises the following steps:

a) respectively and independently crushing various bauxite ores of different grades, screening to prepare bauxite ores with the grain diameter of 2-5mm, drying until the moisture content is 0.8%, and putting the bauxite ores into a grinding head bin for later use, wherein the bauxite ores of different grades refer to bauxite ores with the aluminum content of 40% and the aluminum content of 45%;

b) measuring the components of each raw material in a grinding head bin, then feeding the raw materials by using a metering belt scale according to the proportion of 1: 1, feeding the raw materials into a dry-process ball mill for grinding, and obtaining qualified raw material powder by using a high-efficiency powder concentrator, wherein the particle size of the qualified raw material powder is controlled by adjusting the rotating speed, and the particle size of the qualified raw material powder is 30-50 mu m and reaches more than 90%;

c) collecting the obtained qualified raw meal powder by a bag dust collector, and pulping in a dry powder pulping machine, wherein the dry powder amount and the water amount are controlled by a computer during pulping, and the moisture content of the prepared mud is 50%;

d) putting the obtained slurry into a slurry pool to store ageing materials for 35h, pumping the ageing materials into a high-level tank by using a plunger pump, pumping the ageing materials into a spray gun of a spray tower by using the plunger pump to granulate to obtain spherical raw materials, wherein the water content of the spherical raw materials is 2.0%, the particle size of the spherical raw materials is 0.075-1.0mm, and different spray gun spray piece diameters, cyclone piece thicknesses and plunger pump pressures are selected according to the granularity requirements of finished products, wherein the spray piece diameter is 4mm, the cyclone piece thickness is 4mm, and the plunger pump pressure is 1.0 MPa;

e) and (3) feeding the obtained spherical raw material into a rotary kiln for high-temperature calcination, controlling the calcination temperature at 1700 ℃ for 2h to obtain mullite foundry molding sand, cooling the clinker discharged from the kiln to 90 ℃ by a single-cylinder cooler, and conveying the clinker to a finished product warehouse by a pneumatic conveying device to obtain a finished product with the aluminum content of 50%.

The foundry sand products obtained in examples 1 to 3 were subjected to the measurement of technical parameters, and the measurement results are shown in Table 1.

Table 1 test results of each technical parameter

	Example 1	Example 2	Example 3
				Bulk density g/cm3	1.596	1.602	1.599
True density g/cm3	2.96	2.97	2.97
				Apparent porosity%	37.03	38.24	38.89
Water absorption%	20.85	22.15	22.31

The performance of the casting sand finished product prepared by the method is compared with that of the casting sand at home and abroad, and particularly, aiming at the cold-state rupture strength performance, the cold-state rupture strength is detected after the mullite casting sand is prepared into the precoated sand, and the detection result is shown in table 2.

TABLE 2 comparison of cold flexural strengths of various mullite foundry sands produced as precoated sands

The foundry sand with different component contents was compared, and the performance index of the test was the rate of collapse, and the test results are shown in table 3.

TABLE 3 comparison of the rate of collapse (i.e., collapsibility) of the mullite foundry sand

As can be seen from the tables 1 to 3, the mullite foundry sand prepared by the invention has appropriate physical parameters, and compared with other foundry sand at home and abroad, the precoated sand prepared by the invention has higher cold rupture strength and better performance, and the performance is better along with the increase of the resin doping amount, and the obtained mullite foundry sand has Al of₂O₃The content is obviously higher than that of other sands, and the collapsibility is better.

The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without the use of the inventive faculty. Therefore, the present invention is not limited to the above-described embodiments. Those skilled in the art should appreciate that many modifications and variations are possible in light of the above teaching without departing from the scope of the invention.