Calcareous refractory clinker production method

Abstract

The invention relates to a production method of a calcareous refractory clinker, which comprises the following steps: mixing a CaO-containing raw material and an inhibitor, agglomerating, and calcining at 1350-1550 DEG C to obtain a clinker; the mass percentage of the inhibitor in the mixture is 0.5%-4%; the granularity of the CaO-containing raw material is less than 1mm, and the mass percentage of the CaO-containing raw material with the granularity less than 0.5 mm is not less than 50% The method has the advantages that the natural mineral limestone with lower cost is directly introduced as a raw material in the preparation process, the inhibitor is added, and the clinker is produced in one step through simple calcination, so that the problem of delayed hydration of the lime clinker is solved.

Description

Technical Field

[0001] The invention belongs to the field of refractory materials, and in particular relates to a method for producing lime-based refractory clinker. Background Art

[0002] The hydrophilicity of vacuum smelting limestone refractory increases the difficulty of production and use. Researching and producing a lime clinker that can delay the hydration of the material to make it usable is a prerequisite. Because limestone refractory has a high melting temperature, low decomposition oxygen pressure and steam pressure, and can capture non-ferrous impurities such as Al2O3 in molten steel, it has the function of purifying molten steel. At present, limestone refractory is widely used only in vacuum smelting because the amount used is small and most of them are stored in vacuum tanks, which can prevent the material from contacting with water to a certain extent.

[0003] In recent years, attempts have been made to apply it in steel production, such as molten steel filters, tundish dry materials, etc., but it has not been promoted. The reason is that the hydrophilicity of the material leads to high requirements for production (connection between processes), storage, and use environment, which affects the use of the material. Summary of the invention

[0004] The purpose of the present invention is to provide a method for producing limestone refractory clinker, which can delay the hydration time of hydrated limestone refractory materials and meet the needs of vacuum smelting and conventional steel production.

[0005] To achieve the above object, the present invention is implemented through the following technical solutions:

[0006] A method for producing lime-based refractory clinker comprises mixing a raw material containing CaO and an inhibitor, and calcining the mixture at 1350-1550°C to obtain clinker; the inhibitor accounts for 0.5%-4% by mass of the mixed material; the particle size of the raw material containing CaO is less than 1 mm, and the mass percentage of particles with a particle size less than 0.5 mm is not less than 50%.

[0007] The mass percentage of CaO in the CaO-containing raw material is above 92%.

[0008] The CaO-containing raw material is natural limestone, or a raw material containing more than 98% CaO by mass, or a mixture of natural limestone and a raw material containing more than 98% CaO by mass.

[0009] The inhibitor is a calcium salt.

[0010] The weight gain rate of the clinker placed in air for 10 days is less than 1.0%.

[0011] The mass percentage of CaO in the clinker is 90% to 98%.

[0012] The agglomeration is carried out by using a hydraulic brick press or a friction brick press to press the mixed material to form a standard brick blank.

[0013] Compared with the prior art, the present invention has the following beneficial effects:

[0014] 1. The present invention directly introduces low-cost natural mineral limestone as raw material during the preparation process, adds inhibitors, and produces clinker through a simple calcination step, thereby solving the problem of delayed hydration of lime clinker. The use of lime refractory materials will not be limited to vacuum smelting. Due to the many advantages of lime refractory materials, they will be widely used, especially in the steel industry.

[0015] 2. The production process of the present invention is simple, the obtained clinker particles do not need to be crushed and can be used directly, have good anti-hydration performance, and reduce the requirements on production (connection between processes), storage, and use environment.

[0016] 3. The compressive strength of the lime refractory clinker produced by the present invention is greater than 50MPa, the CaO content is 90-98%, and the bulk density is greater than 2.75g / cm 3 The weight gain of block clinker after being placed in the air for 10 days is less than 1.0%. If it is placed for a long time, it should be sieved before use. DETAILED DESCRIPTION

[0017] The present invention is described in detail below, but it should be noted that the implementation of the present invention is not limited to the following embodiments.

[0018] Example 1

[0019] The method for producing lime refractory clinker comprises the following steps:

[0020] 1) Natural limestone is crushed and sieved to obtain a particle size of less than 1 mm, wherein the mass percentage of the particle size <0.5 mm is not less than 50%.

[0021] 2) Mixing the natural limestone obtained in step 1) with calcium salt, wherein the amount of calcium salt added is 0.8% or 3.8% of the mixture; the calcium salt can be calcium chloride.

[0022] 3) After mixing, the bricks are made into standard bricks of 230mm×114mm×65mm using a hydraulic brick press or a friction brick press. The hydraulic brick press has a molding pressure of 80 to 100 tons, while the friction brick press can use 148 to 152 tons, and the number of hammer blows shall not be less than 2.

[0023] 4) Calcination and sintering: send the block-shaped raw materials into a box-type electric furnace or a tunnel kiln (a box-type electric furnace is used for small output, and a tunnel kiln is used for large output), and heat up at a rate of 3-5°C / min below 500°C and a rate of 5-8°C / min above 500°C, and calcine at 1400-1500°C, keep warm for 120 minutes, and then cool naturally to below 50°C before taking out of the furnace.

[0024] 5) The finished clinker is placed in a sealed silo and can be placed in a dry warehouse for short-term use.

[0025] The finished product is subjected to a hydration test, the finished product is broken into small pieces, and the weight gain rate of the block clinker is less than 0.7% when placed in the air for 10 days.

[0026] Example 2

[0027] The method for producing lime refractory clinker comprises the following steps:

[0028] 1) Prepare a raw material containing more than 98% CaO by mass and a particle size of less than 1 mm, wherein the mass percentage of particles with a size less than 0.5 mm is not less than 50%.

[0029] 2) Mixing the raw material obtained in step 1) with calcium salt, wherein the amount of calcium salt added is 2.8% of the mixed material, and the calcium salt can be calcium chloride.

[0030] 3) After mixing, the bricks are made into standard bricks of 230mm×114mm×65mm using a hydraulic brick press or a friction brick press. The hydraulic brick press has a molding pressure of 85 to 90 tons, while the friction brick press can use 149 to 151 tons, and the hammering times shall not be less than 2.

[0031] 4) Calcination and sintering: send the block-shaped raw materials into a box-type electric furnace or a tunnel kiln (a box-type electric furnace is used for small output, and a tunnel kiln is used for large output), and heat up at a rate of 3-4°C / min below 500°C and a rate of 5-7°C / min above 500°C, and calcine at 1420-1460°C, keep warm for 120 minutes, and then cool naturally to below 50°C before taking out of the furnace.

[0032] 5) The finished clinker is placed in a sealed silo and can be placed in a dry warehouse for short-term use.

[0033] Example 3

[0034] The method for producing lime refractory clinker comprises the following steps:

[0035] 1) Prepare raw materials containing more than 98% CaO by mass and natural limestone in a weight ratio of 3:5, and grind and screen to obtain raw materials with a particle size of less than 1 mm, wherein the mass percentage of particles less than 0.5 mm is not less than 50%.

[0036] 2) Mixing the raw material obtained in step 1) with calcium salt, wherein the amount of calcium salt added is 0.6% to 3.5% of the mixed material.

[0037] 3) After mixing, the bricks are made into standard bricks of 230mm×114mm×65mm using a hydraulic brick press or a friction brick press. The hydraulic brick press has a molding pressure of 80 to 95 tons, while the friction brick press can use 148 to 152 tons, and the hammering times shall not be less than 2.

[0038] 4) Calcination and sintering: send the block-shaped raw materials into a box-type electric furnace or a tunnel kiln (a box-type electric furnace is used for small output, and a tunnel kiln is used for large output), and heat up at a rate of 3 to 4 °C / min below 500 °C and a rate of 6 to 8 °C / min above 500 °C, and calcine at 1440 to 1480 °C, keep warm for 120 minutes, and then cool naturally to below 50 °C before taking out of the furnace.

[0039] 5) The finished clinker is placed in a sealed silo and can be placed in a dry warehouse for short-term use.

[0040] The present invention directly introduces low-cost natural mineral limestone as raw material during the preparation process, adds inhibitors, and produces clinker through a simple calcination step, thereby solving the problem of delayed hydration of lime clinker. The use of lime refractory materials will not be limited to vacuum smelting. Due to the many advantages of lime refractory materials, they will be widely used, especially in the steel industry.

Claims

1. A method for producing limestone refractory clinker, characterized in that: The raw material containing CaO and the inhibitor are mixed, and the blocks are calcined at 1350-1550° C. to obtain mature materials; the inhibitor accounts for 0.5%-4% by mass of the mixed materials; the particle size of the raw material containing CaO is less than 1 mm, and the mass percentage of the particle size less than 0.5 mm is not less than 50%.

2. A method for producing limestone refractory clinker according to claim 1, characterized in that: The mass percentage of CaO in the CaO-containing raw material is above 92%.

3. The method for producing limestone refractory clinker according to claim 1, characterized in that: The CaO-containing raw material is natural limestone, or a raw material containing more than 98% CaO by mass, or a mixture of natural limestone and a raw material containing more than 98% CaO by mass.

4. The method for producing limestone refractory clinker according to claim 1, characterized in that: The inhibitor is a calcium salt.

5. The method for producing limestone refractory clinker according to claim 1, characterized in that: The weight gain rate of the clinker placed in air for 10 days is less than 1.0%.

6. The method for producing limestone refractory clinker according to claim 1, characterized in that: The mass percentage of CaO in the clinker is 90% to 98%.

7. The method for producing limestone refractory clinker according to claim 1, characterized in that: The agglomeration is carried out by using a hydraulic brick press or a friction brick press to press the mixed material to form a standard brick blank.