Production of hollow particle continuous casting mold slag using tailings sand and preparation method

Abstract

The present invention relates to a mold slag for producing hollow particle continuous casting using tailings sand and a preparation method. The mold slag is formulated by weight as follows: tailings sand: 20% to 57%; fluorite: 5% to 10%; marble: 19% to 60%; graphite: 5% to 20%; lepidolite: 0.15% to 5%; soda ash: 1% to 15%; bentonite: 3% to 8%; and binder: 5% to 15%. The present invention provides thermal insulation, prevents heat dissipation, prevents secondary oxidation of molten steel, absorbs inclusions that float to the surface of the molten steel, lubricates the moving ingot, and uniformly regulates heat transfer from the solidifying shell to the crystallizer. The present invention reduces the possibility of mold slag being drawn into the molten steel in the crystallizer. By coordinating the viscosity, melting point, and solidification viscosity temperature characteristics, the mold slag is well lubricated and heat transfer characteristics are controlled, thereby reducing cracks and steel breakouts, and ensuring smooth continuous casting.

Description

Technical field:

[0001] The invention relates to producing hollow particle continuous casting protective slag by utilizing tailings sand and a preparation method thereof. Background technology:

[0002] In the early 1990s, the varieties of die casting and continuous casting in my country were extremely monotonous, the output of continuous casting billets was not high, and there were not many varieties of protective slag. The raw materials for producing composite protective slag by using tailings sand discharged from graphite beneficiation were tailings sand, fluorite, acidified graphite, binder and other raw materials. At the beginning, composite slag was mainly used to solve the three-in-one protective slag, exothermic agent (insulating agent), and insulation board, reduce costs, realize two-in-one casting, and eliminate exothermic agent (insulating agent). It was a primary product that could meet the protective slag requirements used by steel mills at that time.

[0003] Defects of protective slag before the 1990s: Improper selection or use of protective slag at that time caused problems in mold casting and continuous casting processes, continuous accidents, and poor quality of ingots and billets. The lack of detection methods for protective slag resulted in poor stability of the protective slag. The main reason for steel leakage in continuous casting in the past was that the melting temperature of the protective slag was too high and the melting speed was too low, which caused steel leakage, various cracks such as transverse and longitudinal cracks in the billet, and surface quality defects of the billet, all of which were related to the protective slag. Summary of the invention:

[0004] The present invention aims to utilize tailings sand to produce mold slag for continuous casting of hollow particles and a preparation method thereof. Tailings sand has been widely used, has physical and chemical properties close to those required for mold slag, is uniform in composition, has stable quality, eliminates the need for secondary crushing, and is low in cost, making it an ideal mold slag base material and a preparation method thereof. The technical solution of the present invention is to utilize tailings sand to produce mold slag for continuous casting of hollow particles, characterized in that the mold slag is prepared by weight as follows: tailings sand: 20% to 57%; fluorite: 5% to 10%; marble: 19% to 60%; graphite: 5% to 20%; lepidolite ore: 0.15% to 5%; soda ash: 1% to 15%; bentonite: 3% to 8%; and binder: 5% to 15%.

[0005] Binder: Use secondary sodium carboxymethyl cellulose to make the solution.

[0006] The preparation method of the present invention comprises the following steps: (a) crushing raw materials: crushing marble, fluorite and bentonite in a high-fine crusher; (b) crushing tailings sand, marble, fluorite and bentonite in a crushing and drying machine, wherein the crushing part is suitable for crushing various ores, the feed particle size is 1 to 30 mm, and the high-fine powder processing is performed, and the formed particles are adjusted in the range of 80 to 425 meshes; the drying part adopts a downstream drying process, and the ore slag enters into contact with high-temperature hot air and the water vapor is quickly evaporated and then drawn away by the induced wind, thereby achieving the purpose of drying the ore slag. The ore slag is dried in this area to a moisture content of less than 5%, meeting the design particle size and moisture requirements; (c) the tailings sand, marble, fluorite and bentonite are passed through a vibrating screen, and the raw materials are screened through a vibrating screen (minus 200 meshes). The powder is stored separately for use, and the large particles are returned for re-crushing; (d) Fully automatic electronic batching machine: protective slag is prepared according to weight percentage: tailings sand: 20% to 57%; fluorite: 5% to 10%; marble: 19% to 60%; graphite: 5% to 20%; lepidolite ore: 0.15 to 5%; soda ash: 1% to 15%; bentonite: 3% to 8%; binder: 5% to 15%; (e) the ground powder less than or equal to 200 mesh is added to the tailings sand in the first step, marble in the second step, graphite powder in the third step, fluorite in the fourth step, soda ash in the fifth step, and bentonite in the sixth step. The prepared materials are put into a high-speed mixer and stirred for 20 to 50 minutes. The mixing tank is filled with 30 to 70% of the powder by weight. , the rest is water and mixed and stirred for 50 to 80 minutes. The secondary sodium carboxymethyl cellulose is used to make a solution. Industrial water below 25 degrees Celsius is injected into the reactor, and 5% to 15% is added. However, the heating temperature should not be too high. The appropriate range is 50 to 60 degrees Celsius. The heating time is 3 to 6 minutes. Stir evenly at the same time to make a solution. The specific gravity of the sodium carboxymethyl cellulose powder gel is 1.5 to 1.8. The raw materials required for making protective slag are added to the colloidal sodium carboxymethyl cellulose powder gel, including tailings sand, marble, graphite powder, fluorite, soda ash, and bentonite. The weight of the raw materials is 1.5 to 3.0 times that of the sodium carboxymethyl cellulose powder gel. Stir evenly and then send it into the first-level stirring tank and stir it at high speed for 15 to 30 minutes to make the gel liquid Stir evenly; (f) send the slurry produced in the previous step into a water-mill pulping machine for uniform mixing and grinding, and send it to the next process after the particle size test passes 325 mesh; (g) use a high-pressure pump to spray the slurry stirred in the previous step with an atomizing nozzle at a pressure of 1 to 10 MPa in a vacuum drying chamber with a vacuum degree of 0 to 380 mm Hg and a temperature of 600 to 700 degrees to granulate it into 0.15 to 1.0 mm and 0.2 to 0.5 mm hollow continuous casting protective slag, which is dried into a hollow continuous casting protective slag with a bulk density of 0.45 to 0.9 g / cubic centimeter during the falling process; (h) vibrate the product to pass 0.5 mm; (i) after screening, enter the fully automatic packaging machine for packaging; (j) conduct inspection, and (k) finally the finished product is inspected and put into storage.

[0007] Technical effects of the present invention:

[0008] With the rapid development of the steel industry and increasingly fierce market competition, mold slag manufacturers are currently seeking low-cost raw materials. How to produce higher-quality products at a lower cost has become a top priority for steel companies. Tailings sand is used to produce hollow particle continuous casting mold slag. Tailings sand is the base material for mold slag because it is a mature application with physical and chemical properties close to the requirements for mold slag used by steel mills. It eliminates the need for secondary crushing and has a uniform composition, a low melting point, a fast melting rate, and low cost.

[0009] Comparison of raw materials and processes of current protective slag with those in the past: Bentonite is used in current protective slag to replace the expensive expanded graphite products in the past. Bentonite is porous, lubricating, breathable and heat-resistant. During pouring, bentonite expands rapidly in the particles. In the production of refractory materials, it plays the role of heat preservation of high-temperature resistant materials with low cost. Starch is used instead of asphalt as a binder. Asphalt binder is harmful to production plants and steel mills, as well as to human health. Starch is now used instead of asphalt as a binder. The starch is made into a colloidal starch gel, added to the protective slag raw material, and a spray granulator is used to make hollow particle protective slag with better dispersibility.

[0010] The present invention uses tailings sand to eliminate secondary crushing in the process flow, reduce raw materials, and eliminate the need for other protective slag plants to add processes such as melting raw materials in a high-temperature furnace, water quenching, drying, and crushing, which increases costs. Therefore, from the perspective of the process flow, it is obvious that using tailings sand to produce hollow particle continuous casting protective slag has obvious competitiveness.

[0011] The present invention utilizes tailings sand to produce hollow particle continuous casting protection slag to mainly solve the following prominent problems: 1. cost pressure; 2. the existing protection slag has performance problems such as longitudinal cracks in the casting, poor surface quality, and serious slag inclusion.

[0012] The present invention mainly solves the above-mentioned problems through ideas and technical solutions: protective slag is usually a mixture of components such as calcium oxide, silicon dioxide, aluminum oxide, magnesium oxide, etc. Now, according to the process requirements of the steel grade, the protective slag is made to achieve the required physical properties by adjusting the content of other components, and one to multiple new components are introduced to replace them, so as to achieve the design requirements of the original slag performance. Adapting to the diverse requirements of the steel market, 1. Using tailings sand as the base material for protective slag solves the problem of low cost. The original tailings sand has been maturely applied, with stable quality, uniform composition, low melting point, and no need for secondary crushing; 2. Bentonite replaces expanded graphite. Bentonite is porous, lubricating, breathable, and heat-resistant. During pouring, bentonite expands rapidly in the particles. In the production of refractory materials, it plays the role of heat preservation of high-temperature resistant materials; 3. Lepidolite ore can significantly reduce the melting temperature of protective slag, increase the melting speed, improve its fluidity and adhesion, destroy the chain structure of protective slag, and at the same time improve the melting performance of protective slag, avoid the precipitation of high-melting-point crystals, and is an ideal flux; 4. Sodium fluoride and calcium fluoride can lose The network structure of silicate increases its content and has the function of reducing the melting temperature of the protective slag and lowering its viscosity; 5. The binder starch replaces asphalt. Asphalt is used in production and steel mills and is harmful to human health. Starch is an organic compound that works together with microparticle carbon to control the uniform melting rate of the protective slag and has better dispersion. Starch is used to make a solution to make hollow particle continuous casting protective slag, which stabilizes production and improves quality; 6. The speed of carbon particles controlling the melting rate depends on the amount of carbon particles added. Carbon is a high-temperature resistant material. The extremely fine carbon powder is adsorbed around the slag particles, separating the slag particles from each other, hindering the contact and fusion between the slag materials, slowing down the melting rate, and improving the lubrication speed of the protective slag to ensure good lubrication of the casting and control of heat transfer characteristics.

[0013] Through the above-mentioned adjustment of the protective slag composition, the above-mentioned problems of longitudinal cracks in the ingot, poor surface quality and serious slag inclusion are solved in terms of organizational formula and technology. The mechanism of the influence of composition on the performance of the crystallizer is studied. By adjusting the carbon amount, the lubrication speed of the protective slag is increased, and the alkalinity is increased to make the fluidity of the protective slag stronger. Starting from the control of the heat transfer mechanism, the surface quality of the steel billet is effectively improved, and the probability of the occurrence of longitudinal cracks on the steel billet surface is essentially reduced. The longitudinal cracks on the surface of the produced steel billet are greatly reduced, the creases are uniform, and the surface of the steel billet is flat and smooth. The protective slag in the crystallizer has good spreadability. Combined with the various physical property requirements of the protective slag, the composition range of each component is developed and determined, and the production of hollow particle continuous casting protective slag using tailings sand is successfully developed, which is more efficient than traditional protective slag.

[0014] The protective slag of the present invention has a low melting point, an improved melting speed, and appropriate viscosity, which can reduce the involvement of the protective slag in the crystallizer into the molten steel. Through the coordinated control of the viscosity, melting point and solidification viscosity temperature characteristics, good lubrication of the casting and control of heat transfer characteristics are ensured, thereby reducing the casting crack defects and steel leakage accidents, and ensuring smooth continuous casting.

[0015] Specific implementation: In the specific implementation, the binder name is given as an example.

[0016] Tailings sand is used to produce hollow particle continuous casting protective slag, and the protective slag is prepared according to the following weight percentages: tailings sand: 20% to 57%; fluorite: 5% to 10%; marble: 19% to 60%; graphite: 5% to 20%; lepidolite ore: 0.15% to 5%; soda ash: 1% to 15%; bentonite: 3% to 8%; and binder: 5% to 15%.

[0017] Binder: Use secondary sodium carboxymethyl cellulose to make the solution.

[0018] Preparation process of hollow particle continuous casting mold slag using tailings sand:

[0019] (a) Raw material crushing: marble, fluorite and bentonite are crushed in a high-fine crusher; (b) tailings sand, marble, fluorite and bentonite are crushed and dried in a crushing dryer. Crushing part: suitable for crushing various ores, feed particle size: 1-30mm, high-fine powder processing, formed particles are adjusted in the range of 80-425 mesh; drying part: the equipment adopts a downstream drying process, the ore and slag enter the high-temperature hot air contact and quickly evaporate the water vapor and then are drawn away by the induced air, thereby achieving the purpose of drying the ore and slag. The ore and slag are dried in this area to a moisture content of less than 5%, meeting the design particle size and moisture requirements; (c) tailings sand, marble, fluorite and bentonite are passed through a vibrating screen, and the raw materials are stored separately after passing through a vibrating screen (minus 200 mesh) for use. Large particles are returned for re-crushing; (d) Fully automatic electronic batching machine: protective slag is prepared according to weight percentage: tailings sand: 20% to 57%; fluorite: 5% to 10%; marble: 19% to 60%; graphite: 5% to 20%; lepidolite ore: 0.15 to 5%; soda ash: 1% to 15%; bentonite: 3% to 8%; binder: 5% to 15%; (e) the ground powder less than or equal to 200 mesh is added to the tailings sand in the first step, marble in the second step, graphite powder in the third step, fluorite in the fourth step, soda ash in the fifth step, and bentonite in the sixth step. The prepared materials are put into a high-speed mixer and stirred for 20 to 50 minutes. The mixing tank contains 30 to 70% of the powder by weight, and the rest is water. The secondary sodium carboxymethyl cellulose is made into a solution. Industrial water below 25 degrees Celsius is injected into the reactor, and 5% to 15% is added. However, the heating temperature should not be too high. The suitable range is 50 to 60 degrees Celsius. The heating time is 3 to 6 minutes. Stir evenly at the same time to make a solution. The specific gravity of the sodium carboxymethyl cellulose powder gel is 1.5 to 1.8. The raw materials required for making protective slag are added to the colloidal sodium carboxymethyl cellulose powder gel, including tailings sand, marble, graphite powder, fluorite, soda ash, and bentonite. The weight of the raw materials is 1.5 to 3.0 times that of the sodium carboxymethyl cellulose powder gel. Stir evenly and then send it into the first-level stirring tank and stir it at high speed for 15 to 30 minutes to stir the gel liquid. Uniform; (f) the slurry produced in the previous step is sent to a water-mill pulping machine for uniform mixing and grinding, and the particle size test is passed 325 mesh and then sent to the next process; (g) the slurry stirred in the previous step is sprayed and granulated into 0.15-1.0 mm, 0.2-0.5 mm hollow continuous casting protective slag by using a high-pressure pump at a pressure of 1-10 MPa and an atomizing nozzle in a vacuum drying chamber with a vacuum degree of 0-380 mm Hg and a temperature of 600-700 degrees. The hollow continuous casting protective slag is dried into a hollow continuous casting protective slag with a bulk density of 0.45-0.9 g / cubic centimeter during the falling process; (h) the product is vibrated to pass 0.5 mm; (i) after screening, it is packaged in a fully automatic packaging machine; (j) inspection is carried out, and (k) the finished product is finally inspected and put into storage.

[0020] The tailings sand used in the present invention is a mature and reasonable raw and auxiliary material with stable quality, recycled waste ore, low cost and simple production process to provide protective slag.

[0021] The raw and auxiliary materials used can meet the user's requirements. Tailings sand is an ideal raw material because it is rich in raw material resources, low in price, contains no harmful gases, and does not pollute the environment.

[0022] The present invention utilizes tailings to produce hollow particle continuous casting protective slag, which is a high value-added product with low cost and solves the defects of poor quality of casting billets, cracks, steel leakage and the like. The production process is simple, stable and reasonable. The hollow particles produced are uniform and have high strength at room temperature. Tailings sand is used to produce hollow particle continuous casting protective slag, which has strong casting and inclusion absorption capacity, good spreadability and good thermal insulation. The waste tailings sand is comprehensively utilized to turn waste into treasure, reducing the adverse effects of waste tailings sand stacking on environmental protection. In order to improve the quality of casting billets, ensure smooth casting and obtain defect-free surface quality of casting billets, the tailings sand can be made into a good refractory material for steel metallurgy and give full play to the role of tailings sand in protective slag, which will definitely have obvious social and economic benefits.

Claims

1. A process for producing hollow particle continuous casting mold slag using tailings sand, characterized by: (a) Raw material crushing: crush marble, fluorite and bentonite in a high-fine crusher; (b) Tailings sand, marble, fluorite and bentonite are crushed and dried in the crushing and drying machine. The crushing part is suitable for crushing various ores, with feed particle size of 1~30mm, high-fine powder processing, and the formed particles are adjusted in the range of 80~425 mesh; the drying part adopts the downstream drying process, and the ore and slag enter the high-temperature hot air and quickly evaporate the water vapor, which is then drawn away by the induced wind, thereby achieving the purpose of drying the ore and slag. The ore and slag are dried to a moisture content of less than 5% in this area, meeting the design particle size and moisture requirements; (c) Tailings sand, marble, fluorite and bentonite are passed through a vibrating screen, and the raw materials are stored separately after passing through a minus 200 mesh vibrating screen for standby use, and the large particles are returned for re-crushing; (d) Fully automatic electronic batching Machine: The protective slag is prepared by weight percentage: tailings sand: 20% to 57%; fluorite: 5% to 10%; marble: 19% to 60%; graphite: 5% to 20%; lepidolite ore: 0.15% to 5%; soda ash: 1% to 15%; bentonite: 3% to 8%; binder: 5% to 15%; (e) The ground powder less than or equal to 200 mesh is added to the tailings sand in the first step, marble in the second step, graphite powder in the third step, fluorite in the fourth step, soda ash in the fifth step, and bentonite in the sixth step. The prepared materials are put into a first-level high-speed mixer and stirred for 20 to 50 minutes. The mixing tank is mixed and stirred in a ratio of 30 to 70% by weight of the powder and the rest of the water for 5 minutes. 0 to 80 minutes, secondary sodium carboxymethyl cellulose is used to make gel, industrial water below 25 degrees Celsius is injected into the reactor, 5% to 15% is added, the heating temperature is not suitable for being too high, the suitable range is 50 degrees Celsius to 60 degrees Celsius, the heating time is 3 to 6 minutes, and the mixture is stirred evenly at the same time. The specific gravity of sodium carboxymethyl cellulose gel is 1.5 to 1.8, and the raw materials required for making protective slag are added to the colloidal sodium carboxymethyl cellulose gel, including tailings sand, marble, graphite powder, fluorite, soda ash, and bentonite. The weight of the raw materials is 1.5 to 3.0 times that of the sodium carboxymethyl cellulose gel. The mixture is stirred evenly and then sent to the first-level stirring tank for high-speed stirring for 15 to 30 minutes to stir the gel evenly; (f) the raw materials in the previous step are added to the colloidal sodium carboxymethyl cellulose gel and the raw materials are added to the first-level stirring tank for high-speed stirring for 15 to 30 minutes to stir the gel evenly. The slurry produced in the first step is sent to a water-mill pulping machine for uniform mixing and grinding. If the particle size is detected to be 325 mesh, it is sent to the next process; (g) the slurry stirred in the previous step is sprayed and granulated into 0.15-1.0 mm and 0.2-0.5 mm hollow continuous casting protection slag using a high-pressure pump at a pressure of 1-10 MPa and an atomizing nozzle in a vacuum drying chamber with a vacuum degree of 0-380 mm Hg and a temperature of 600-700 degrees. The hollow continuous casting protection slag is dried into a bulk density of 0.45-0.9 g / cubic centimeter during the falling process; (h) the product is vibrated to pass 0.5 mm; (i) after screening, it is sent to a fully automatic packaging machine for packaging; (j) inspection is carried out, and (k) the finished product is finally inspected and put into storage.