CN-122010128-A - Process for reducing talcum powder moisture and improving yield by high-temperature compressed gas

Abstract

A process for reducing the water content of talc powder and increasing its output by high-temp compressed gas includes such steps as starting system, setting the target water content of final product, setting the initial temp. parameters of drying units, continuously and stably feeding the wet talc powder with 2-8% of initial water content to multi-stage serially connected preheating conveyers (for example, flowing from third stage to second stage, and finally to first stage, and the opposite flowing direction of hot air), and pre-drying by afterheat of system. The invention realizes deep coupling and synergistic effect of drying and depolymerization, namely, the water content is reduced from 0.7% to 0.1% under the conditions of 80 ℃ high-temperature gas and 8MPa pressure, the yield is improved by 35%, and the process of 'source high-temperature dehydration + pipeline heat preservation + precise pressure control' is integrated, so that the problem of industry pain points with high energy consumption and large water fluctuation in the traditional post-stage drying is solved.

Inventors

• GAO QUAN

Assignees

• 后英集团海城市水泉滑石矿有限公司

Dates

Publication Date

20260512

Application Date

20260119

Claims (6)

1. 1. A process for reducing talcum powder moisture and improving yield by high-temperature compressed gas is characterized by comprising the following steps: A. Starting a system, setting a target moisture value of a final product, setting initial temperature parameters of each stage of drying unit, continuously and stably feeding wet-smooth stone powder raw materials with initial moisture content of 2% -8% into a multi-stage serial preheating conveyor (for example, flowing from a third stage to a second stage, finally entering the first stage, and enabling hot air to flow in the opposite direction), pre-drying wet materials by utilizing system waste heat, wherein the temperature of the pre-dried materials is increased, the moisture of the materials is reduced, the materials enter a next stage of drying unit, meet with waste gas with higher temperature from a previous stage, carry out deep drying, and the pre-dried materials enter a feeding port of a gas jet drying depolymerization reactor and contact with fresh hot air with highest temperature provided by a main heater; B. High-temperature compressed gas jet impact and instantaneous drying depolymerization, namely, high-temperature high-pressure gas is introduced into a gas jet drying depolymerization reactor, and is subjected to instantaneous decompression expansion at the bottom or tangential inlet of a flash drying tower through a special designed Laval nozzle or decompression nozzle, the gas volume is rapidly expanded, the temperature is slightly reduced and still at high temperature, and simultaneously, extremely high flow speed and strong turbulence are generated, and preheated wet-smooth powder is quantitatively added from the top or the other side of the tower and meets the high-speed high-temperature gas flow; C. The gas-solid separation and product collection are carried out, namely, gas-solid two-phase flow which is instantaneously dried and depolymerized is completed, the top of a drying tower enters a high-efficiency cyclone separator to carry out primary separation, most of fine powder products which are qualified by drying are collected, then dust-containing tail gas enters a bag dust remover or a filter cartridge dust remover to carry out secondary fine separation, the captured superfine powder is singly collected as a high-added value product, most of separated high-temperature tail gas is returned to the air inlet end of a high-temperature high-pressure air source system, and the rest is introduced into a waste heat recovery device to be circularly used for preheating fresh air or raw materials; D. And cooling and post-treating the product, namely, the talcum powder product collected from the cyclone separator, the cloth bag dust collector or the filter cartridge dust collector has higher temperature, and the talcum powder product needs to enter a fluidized bed cooler or a cooling screw conveyor, is cooled to below 40 ℃ by normal-temperature air or cooling water, and is subjected to screening and deironing to obtain the final talcum powder product with low moisture and high dispersibility.
2. 2. A process for reducing the moisture content and increasing the yield of talcum powder by high-temperature compressed gas according to claim 1, wherein the drying unit in the step A is a combination of a stirring dryer, a tray dryer or an air flow drying pipe, and the following synergistic effects occur in the mixing stage, namely a) ultra-fast heat and mass transfer, namely huge sensible heat carried by the high-temperature gas is instantaneously transferred to talcum powder particles through extremely high gas-solid phase contrast speed, b) particle depolymerization and refinement, namely strong shearing force and inter-particle collision force generated by high-pressure high-speed air flow, and meanwhile, micro-explosion effect generated by instantaneous vaporization of moisture in the particles, and c) wrapping water removal, namely micro-explosion effect and strong turbulence disturbance.
3. 3. The process for reducing talcum powder moisture and improving yield by using high-temperature compressed gas according to claim 1, wherein the high-temperature and high-pressure gas preparation method in the step B is characterized in that a) air or inert gas at normal temperature and normal pressure is compressed to 8MPa by an air compressor to obtain high-pressure gas, B) the high-pressure gas is introduced into a gas heater or an electric heater and is rapidly heated to 400-650 ℃ to form high-temperature and high-pressure gas, the mass ratio of the high-temperature and high-pressure gas to wet talcum powder is controlled to be in the range of 4:1-10:1), meanwhile, a stirrer or a crushing device is arranged at the bottom of a flash drying tower, and a gas jet drying and depolymerizing reactor can be designed into a opposite-spraying type, vortex cavity type or annular gap accelerating type structure.
4. 4. A process for reducing talcum powder moisture and increasing yield by high-temperature compressed gas according to claim 1 is characterized in that in the step B, after meeting, in extremely short residence time, the following processes occur, namely a) ultra-strong heat and mass transfer, namely extremely high gas-solid phase-contrast speed and huge contact area, so that heat of the high-temperature gas is instantaneously transferred to wet talcum powder particles, the interior and surface moisture of the wet talcum powder particles are rapidly vaporized, and B) strong depolymerization, namely strong shearing force generated by high-speed airflow and collision and friction among the particles, can effectively break up initial agglomerates of the wet talcum powder, and prevent secondary agglomeration in the process of rapid moisture evaporation, and play a role in synchronous drying and depolymerization.
5. 5. The process for reducing talcum powder moisture and improving yield by using high-temperature compressed gas according to claim 1, further comprising online moisture detection and self-adaptive feedback control, wherein the pre-dried material is subjected to real-time detection of moisture content by an online moisture detector, detection signals are transmitted to an intelligent control system in real time, if the detected moisture is higher than a target value, the control system judges that the drying strength is insufficient, the process is synchronously executed, namely, a) the power of a main heater is properly increased, the inlet air temperature of a first-stage drying unit is increased, b) the feeding rate is properly reduced so as to prolong the residence time of the material in the most critical first-stage drying unit, and if the detected moisture is lower than the target value, the control system judges that the drying is excessive and the energy consumption is wasted, the process is synchronously executed, namely, a) the power of the main heater is properly reduced, b) the feeding rate is properly increased, and the yield is maximized on the premise that the product moisture is ensured to be qualified.
6. 6. A process for reducing talc moisture and increasing yield by a high temperature compressed gas according to claim 5 wherein said intelligent control system employs a fuzzy PID control algorithm to respond more smoothly and rapidly to moisture fluctuations.

Description

Process for reducing talcum powder moisture and improving yield by high-temperature compressed gas Technical Field The invention relates to the technical field of talcum powder production, in particular to a process for reducing talcum powder moisture and improving yield by high-temperature compressed gas. Background Talcum powder is used as an important industrial mineral filler, the application performance (such as whiteness, fineness, oil absorption value, moisture content and the like) of the talcum powder directly influences the quality of products such as downstream plastics, coatings, papermaking, cosmetics and the like, wherein the moisture content is one of key indexes, and the existing talcum powder drying process mainly has the following problems: the energy consumption is high, the efficiency is low, the traditional hot air drying (such as flash drying and rotary kiln drying) relies on convection heat transfer, the heat efficiency is low (usually lower than 50%), a large amount of heat energy is required for evaporating moisture, the heat conductivity coefficient of talcum powder is low, and the moisture (especially combined water) is difficult to quickly migrate from the inside of particles to the surface, so that the drying time is long, and the energy consumption is huge. The agglomeration and particle size coarsening of the product are that talcum powder is easy to generate secondary agglomeration due to the evaporation of water, the increase of the surface energy of particles and the adhesion effect among heated particles in the drying process, so that the particle size of the powder is coarsened and the specific surface area is reduced, the drying efficiency is influenced, the service performance (such as dispersibility) of the product is more seriously reduced, and additional mechanical crushing (such as air-jet milling) procedures are needed to be added for depolymerization in the follow-up process, and the complexity and energy consumption of the process flow are increased. Contradiction between productivity and quality, in order to pursue high yield, the drying temperature is often increased or the residence time is prolonged, but this may lead to local overheating of the talc, loss of structural water (at temperatures exceeding 550 ℃) affecting its lamellar structure and electrical properties, even to a decrease in whiteness, and limited yield if the quality is ensured by slow drying at low temperatures. The coating water partially adsorbed in the gaps between fine particles or sheets is difficult to effectively remove in the traditional convection drying mode, so that the residual moisture of the product has large fluctuation, and the requirement of ultra-low moisture content (such as < 0.1%) is difficult to stably reach. Disclosure of Invention The invention aims to provide a process for reducing talcum powder moisture and improving yield by high-temperature compressed gas so as to solve the problems in the prior art. In order to achieve the aim, the invention provides the following technical scheme that the process for reducing the talcum powder moisture and improving the yield by using high-temperature compressed gas comprises the following steps of: A. Starting a system, setting a target moisture value (such as 0.1%) of a final product, setting initial temperature parameters of each stage of drying units, continuously and stably feeding wet-smooth stone powder raw materials with initial moisture content of 2% -8% into a multi-stage serial preheating conveyor (for example, flowing from a third stage to a second stage, finally entering the first stage and enabling hot air to flow in the opposite direction), pre-drying the wet materials by utilizing system waste heat (such as waste gas with the temperature of 90-120 ℃ from a subsequent separator) to reduce the viscosity of the materials and evaporate part of surface water, ensuring the smoothness of feeding, and enabling the temperature of the materials subjected to the pre-drying of the previous stage to be increased, enabling the moisture to be reduced, then entering a next stage of drying unit, meeting the waste gas with higher temperature from the previous stage, carrying out deep drying, enabling the pre-dried materials to enter a feeding port of a gas jet drying depolymerization reactor, and contacting the pre-dried materials with fresh hot air with the highest temperature (such as 400 ℃) provided by a main heater; B. High-temperature compressed gas jet impact and instantaneous drying depolymerization, namely, high-temperature high-pressure gas is introduced into a gas jet drying depolymerization reactor, and is subjected to instantaneous decompression expansion at the bottom or tangential inlet of a flash drying tower through a special-designed Laval nozzle or decompression nozzle, the gas volume is rapidly expanded, the temperature is slightly reduced and still is still at high temperature (for example, from 600 ℃ to 350 ℃)