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CN-122010444-A - Method for reducing water content in slag

CN122010444ACN 122010444 ACN122010444 ACN 122010444ACN-122010444-A

Abstract

The invention discloses a method capable of realizing reduction of water content in slag, which comprises the following steps that A, a low-temperature pre-drying section aims at removing most of free water, wet slag with the initial water content of 15-35% is sent into the pre-drying section, and after the wet slag is discharged from the pre-drying section, the water content of the slag is reduced to 8-15%; and B, the medium-temperature main dehydration section aims at efficiently removing bound water, namely, the pre-dried slag enters the main dehydration section, the stage is a main battlefield for dehydration, and the water content of discharged materials is rapidly reduced to 3% -5%. The invention realizes the optimal balance of deep dehydration and activity protection, and the three-stage temperature path from low-temperature pre-drying (anti-crusting), medium-temperature main dehydration (high-efficiency dehydration) to low-temperature stabilization (deep dehydration and activity restoration) ensures that the final moisture is less than or equal to 2 percent, avoids the damage of high temperature to the activity of slag, and the activity index (such as 7d and 28d strength ratio) of the product is superior to that of the traditional high-temperature drying product.

Inventors

  • QIN YUZHE
  • XIAO BAIXIAN
  • CAO SHIXUAN
  • JIA XIAOLIANG
  • ZHANG JU

Assignees

  • 后英集团海城市建筑材料有限公司

Dates

Publication Date
20260512
Application Date
20260119

Claims (6)

  1. 1. A method for realizing the reduction of the moisture content of slag is characterized by comprising the following steps: A. The aim of the low-temperature pre-drying section is to remove most of free water, namely, wet slag with the initial water content of 15-35% is sent into the pre-drying section, and after the wet slag is discharged from the pre-drying section, the water content of the slag is reduced to 8-15%; B. The medium-temperature main dehydration section aims at efficiently removing bound water, namely, the pre-dried slag enters a main dehydration section, the stage is a main battlefield for dehydration, and the water content of discharged materials is rapidly reduced to 3% -5%; C. The low-temperature active stabilization section aims at deep dehydration and active restoration, namely, the slag after the main dehydration enters the active stabilization section, the moderate negative pressure is maintained at the stage, and the water content of the final discharged material is less than or equal to 2%; D. waste heat gradient utilization and negative pressure regulation, namely, the waste gas discharged from the active stabilizing section is used for preheating cold air or wet materials entering the pre-drying section, the high-temperature waste gas discharged from the main dewatering section firstly passes through a cyclone dust collector to recover fine powder, then enters a spray condensing tower or a heat pump type waste heat recovery system, and the cooled waste gas is recycled to the inlet of the main dewatering section partially and is used for the active stabilizing section or the pre-drying section partially.
  2. 2. A process for achieving moisture reduction in slag according to claim 1, wherein the pre-drying stage in step A is carried out in a high energy ball mill or a high speed mechanical shear activator and is mechanically activated for 10-60 minutes with moderate to high energy intensity by introducing system low temperature waste heat as the main heat source, and then the slag is heated to 120-150 ℃, at which relatively mild temperature free water and part of capillary water between the slag particles are slowly and uniformly evaporated, thereby avoiding surface too fast drying crust formation, leaving a channel for internal moisture migration, and the pre-drying stage operation is carried out under micro negative pressure.
  3. 3. A method for reducing water content in slag according to claim 2, wherein the mechanochemical effect caused by the mechanical activation treatment is that a) the original hydroxyl (-OH) structure on the surface of the slag particles is destroyed, the hydrogen bonding force with water molecules is weakened, b) lattice defects and dislocation are generated on the surface of the slag particles, the surface amorphization degree is increased, the surface energy is changed, and c) partial closed pores are opened.
  4. 4. The method for reducing water content in slag according to claim 1, wherein the main dewatering section in the step B uses gas obtained by mixing high-temperature hot air with medium-temperature waste gas from the pre-drying section as a heat source, the material bed is quickly heated and stabilized in a medium-temperature range of 350-400 ℃ through precise control, and the main dewatering section is operated under significant negative pressure to form strong water escape driving force.
  5. 5. The method for reducing water content in slag according to claim 1, wherein the active stabilization stage in the step C is performed in a belt dryer or a paddle dryer, drying is performed at a lower temperature (70-120 ℃) and under a negative pressure of-0.06 MPa to-0.095 MPa, sensible heat of the material itself and middle-low temperature hot air after heat exchange of high-temperature waste gas from the main dewatering stage are utilized, and the temperature of the material is slowly reduced to be less than or equal to 200 ℃ through precise air quantity control.
  6. 6. The method for reducing water content in slag according to claim 1, wherein the temperature of the waste gas discharged from the active stabilization section in the step D is 120-150 ℃, the temperature of the high-temperature waste gas discharged from the main dehydration section is 450-550 ℃, the negative pressure of the whole system is uniformly established at the tail part by an induced draft fan, and the accurate distribution control is performed through the opening degree of an air valve among the sections, so that the pre-drying section, the main dehydration section and the active stabilization section form a required gradient negative pressure environment.

Description

Method for reducing water content in slag Technical Field The invention relates to the technical field of slag, in particular to a method capable of reducing the moisture content of slag. Background After a large amount of slag generated by smelting iron and steel and nonferrous metals is subjected to wet treatment (such as water quenching and wet piling), the initial water content is usually up to 15% -35%, when the high-humidity slag is used as a cement admixture or a building material raw material, the high-humidity slag not only increases the transportation cost and affects the grinding efficiency, but also obviously reduces the hydration activity of the slag, restricts the utilization of high added value, and the existing dehydration technology faces the contradiction between dehydration depth and activity protection: Traditional thermal drying (such as rotary kiln and drum type drying) is usually carried out by adopting single high temperature (300 ℃) to rapidly dehydrate, and although the water content can be reduced, the high temperature can lead to the inactivation and crystallization of active components (such as amorphous glass bodies and active calcium aluminum phases) in slag, the gelation activity is seriously damaged, and the energy consumption is extremely high. Low temperature drying technology, in order to avoid activity damage, adopts low temperature (< 150 ℃) long time drying, but has slow dehydration rate, difficult deep removal of water to below 2%, long treatment period and poor energy consumption economy. The adaptability to the initial water content is poor, when the fluctuation of the water content of the incoming material is large (15% -35%), the drying process with fixed parameters is difficult to control the final water content and the activity of the product stably, and the insufficient drying or overdrying is easy to occur. Disclosure of Invention The invention aims to provide a method for reducing the water content of slag, which aims to solve the problems in the background technology. In order to achieve the purpose, the invention provides the following technical scheme that the method for reducing the water content of the slag comprises the following steps: A. The aim of the low-temperature pre-drying section (the material temperature is 120-150 ℃) is to remove most of free water, namely, wet slag with the initial water content of 15-35% is sent into the pre-drying section, and after the wet slag is discharged from the pre-drying section, the water content of the slag is reduced to 8-15%; B. The aim of the medium-temperature main dehydration section (the temperature of the materials is 350-400 ℃) is to efficiently remove the bound water, namely, the pre-dried slag enters the main dehydration section, the main dehydration section is a main battlefield for dehydration, and the water content of discharged materials is rapidly reduced to 3-5%; C. The low-temperature active stabilization section (the temperature of the material is less than or equal to 200 ℃) aims at deep dehydration and active restoration, namely, the slag after the main dehydration enters the active stabilization section, the moderate negative pressure (-100 Pa to-200 Pa) is maintained at the stage, and the water content of the final discharged material is less than or equal to 2%; D. waste heat gradient utilization and negative pressure regulation, namely, the waste gas discharged from the active stabilizing section is used for preheating cold air or wet materials entering the pre-drying section, the high-temperature waste gas discharged from the main dewatering section firstly passes through a cyclone dust collector to recover fine powder, then enters a spray condensing tower or a heat pump type waste heat recovery system, and the cooled waste gas is recycled to the inlet of the main dewatering section partially and is used for the active stabilizing section or the pre-drying section partially. Preferably, the pre-drying section in the step A is performed in a high-energy ball mill or a high-speed mechanical shearing activator, and the mechanical activation treatment is performed for 10-60 minutes with medium to high energy intensity (ball-material ratio is 5:1-15:1 and rotating speed is 200-500 rpm) by introducing low-temperature waste heat (such as waste gas of a subsequent cooling section and temperature is 90-120 ℃) of a system as a main heat source, wherein the mechanical energy has the effects of crushing particles, increasing specific surface area, aiming at loosening the combination of moisture and slag particles, particularly weakening the combination force of the combination water, creating favorable conditions for subsequent deep dehydration, and then heating the slag to 120-150 ℃, free water and partial capillary water among the slag particles are slowly and uniformly evaporated at the relatively mild temperature, so that the surface is prevented from being excessively quickly dried and crusted,