Process for roasting and removing organic matters from gibbsite

Abstract

The invention relates to the technical field of organic matter removal, and provides a gibbsite organic matter roasting removal process which comprises the following steps: step 1, mixing foreign gibbsite and domestic diasporic bauxite according to a certain mass ratio; step 2, preparing mineral powder from the mixed ore in final grinding equipment by adopting a dry-method powder preparation process; 3, roasting treatment is conducted in a desulfurization furnace, and the temperature and the retention time of a main furnace reaction area are controlled; and 4, synchronously removing organic matters and inorganic carbon through high-temperature roasting. A nano ceramic anti-sticking coating with a certain thickness is adopted for a discharging port of the final grinding equipment, and the inclination angle of the mineral powder conveying equipment is optimized. The roasting desulfurization process is adopted. A nano ceramic anti-sticking coating with a certain thickness is used on a final grinding device, the inclination angle of a belt mineral powder conveying device is optimized, and a wear-resistant ceramic lining plate is used, so that the productivity is improved; dry-method powder preparation and roasting desulfurization equipment is used; organic matters and inorganic carbon are removed through high-temperature roasting, so that the salt discharge load is reduced by 30%, and the adaptability of mineral types is improved.

Description

Technical Field

[0001] This invention relates to the field of organic matter removal technology, specifically a roasting process for removing organic matter from trihydrate bauxite. Background Technology

[0002] In the alumina production sector, trihydrate bauxite from overseas, due to its abundant reserves and high aluminum content, has become an important raw material for dry powder preparation processes. However, in the preparation of alumina dry powder, this type of ore requires fine processing through final grinding equipment to meet the requirements of subsequent roasting and leaching, and its process adaptability issues are gradually becoming prominent.

[0003] In existing technologies, auxiliary equipment for final grinding (such as raw material bucket elevators) often suffers from incomplete unloading due to the high viscosity of mineral powder. The grinding mill's main rollers also experience slagging issues caused by mineral powder adhesion, which traditional metal liners and ordinary conveyor belts struggle to handle, resulting in low equipment capacity and frequent maintenance. Furthermore, foreign trihydrate bauxite has a high organic content, which existing roasting processes struggle to remove efficiently. This leads to residual organic matter in subsequent solution treatment, affecting alumina dissolution rates. Simultaneously, incomplete removal of inorganic carbon from the ore significantly increases the salt discharge load in the downstream solution, limiting the production system's adaptability to different mineral types. Therefore, there is an urgent need to develop a comprehensive process that balances equipment wear resistance and anti-sticking properties with efficient organic matter removal. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a roasting and decarbonization process for trihydrate bauxite, which solves the problems of material sticking to equipment, high organic matter content, and insufficient decarbonization in the preparation of trihydrate bauxite dry powder.

[0005] To achieve the above objectives, the present invention provides a process for roasting and removing organic matter from trihydrate bauxite, characterized by comprising the following steps:

[0006] Step 1: Mix foreign trihydrate bauxite with domestic monohydrate gibbsite bauxite in a certain mass ratio.

[0007] Step 2: Use a dry grinding process to produce mineral powder from the mixed ore in a final grinding equipment;

[0008] Step 3: Roasting treatment is carried out in the desulfurization furnace, and the temperature and residence time in the main furnace reaction zone are strictly controlled;

[0009] Step 4: Simultaneously remove organic matter and inorganic carbon through high-temperature roasting.

[0010] Preferably, the feed inlet of the final grinding equipment is coated with a nano-ceramic anti-stick coating, and the inclination angle of the mineral powder conveying equipment is optimized.

[0011] Preferably, in the roasting desulfurization process, oxygen-enriched air is introduced and the flow rate is strictly controlled.

[0012] Preferably, the organic matter removal efficiency satisfies the formula:

[0013] η = 1 - e -k·t

[0014] Where k = 0.0032T - 1.75 (T is the calcination temperature), t is the residence time (min), and η ≥ 75%.

[0015] Preferred, including:

[0016] Mixing unit: equipped with a twin-helix agitator;

[0017] Dry milling unit: roller mill with wear-resistant ceramic liner;

[0018] The roasting desulfurization unit consists of a three-stage temperature-controlled reactor with strict temperature gradient control.

[0019] Waste heat recovery unit: Waste heat is transported to the final grinding system via a high-temperature fan.

[0020] Preferably, the inner wall of the furnace chamber of the roasting furnace unit is provided with a silicon carbide coating with a thickness of 50-80μm.

[0021] Preferably, the discharge port of the dry milling unit is equipped with an ultrasonic anti-clogging vibrator with a frequency of 28-35kHz.

[0022] Preferably, the specific surface area of ​​the roasted mineral powder is ≥350m². 2 / g.

[0023] Preferably, the inorganic carbon removal rate is ≥40%, and the salt discharge load of the downstream solution is reduced by 30%.

[0024] Preferably, the moisture content of the mineral powder in step two is ≤8%.

[0025] This invention provides a process for roasting and removing organic matter from trihydrate bauxite. It has the following beneficial effects:

[0026] 1. This invention addresses the issues of incomplete unloading of raw material from the bucket elevator in the final grinding mill and easy material clogging on the rollers of the final grinding mill during the preparation of alumina dry powder from bauxite ore abroad. It employs a nano-ceramic anti-sticking coating of a certain thickness at the feed inlet of the final grinding mill, optimizes the inclination angle of the mineral powder conveying equipment, and uses wear-resistant ceramic liners on easily worn parts of the roller mill. These measures effectively reduce the mineral powder sticking rate to below 3%, increase the mineral powder conveying efficiency by 20%, and thus improve the final grinding capacity.

[0027] 2. This invention utilizes a unique dry grinding process and roasting desulfurization process to remove organic matter through high-temperature roasting, thereby solving the problem of high organic matter content in foreign trihydrate bauxite from the source and forming a production technology suitable for foreign trihydrate bauxite mines.

[0028] 3. By roasting the ore at a certain temperature, ≥40% of inorganic carbon is removed while removing organic matter, reducing the salt discharge load of the downstream solution by 30%, and improving the adaptability of the production system to different minerals by adjusting parameters such as temperature and residence time. Attached Figure Description

[0029] Figure 1 This is a flowchart of the present invention;

[0030] Figure 2 This is a system diagram of the present invention. Detailed Implementation

[0031] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0032] Example 1

[0033] Please see the appendix Figure 1 and attached Figure 2 This invention provides a process for roasting and removing organic matter from trihydrate bauxite, comprising the following steps:

[0034] Step 1: Mix foreign trihydrate bauxite with domestic monohydrate gibbsite bauxite in a certain mass ratio.

[0035] Specifically, trihydrate bauxite from abroad is mixed with monohydrate gibbsite bauxite from China, with the mixing ratio precisely controlled within a certain mass ratio. In particular, when trihydrate bauxite from abroad is mixed with monohydrate gibbsite bauxite from China, the initial content of organic and inorganic matter in the mixed sample and the initial specific surface area of ​​the mixed sample can reach 220 m². 2 The material has a moisture content of 6.5%, which fully meets the process requirement of ≤8% moisture content. It is worth mentioning that the mixing process is carried out in a specially designed ore mixing and stirring device. This device is equipped with a high-precision weighing module, ensuring that the error of each batch is controlled within ±0.1kg. Combined with a twin-shaft paddle stirring system, it ensures that the raw materials are thoroughly and evenly mixed within minutes, allowing for full contact between ore particles and laying a good foundation for subsequent processing.

[0036] Step 2: The mixed ore is finally ground in a final grinding equipment using a dry grinding process. The feed inlet of the final grinding equipment is coated with a nano-ceramic anti-stick coating, and the inclination angle of the ore powder conveying equipment is optimized.

[0037] Specifically, a roller mill with wear-resistant ceramic liners is used, controlling the roller mill pressure and grinding disc speed at 28 rpm, strictly controlling the finished product particle size, with the -200 mesh ratio meeting technical requirements. A nano-ceramic coating at the feed inlet reduces the mineral powder adhesion rate from 15% to below 3%, and the optimized tilt angle of the mineral powder conveying equipment increases conveying efficiency by 20%. A dry grinding process is employed, with the mixed ore undergoing final grinding in the final grinding equipment. The selected final grinding equipment is a roller mill with wear-resistant ceramic liners, with strict and precise control of roller mill pressure, grinding disc speed, and finished product particle size. To solve the problem of mineral powder adhesion to the walls, the feed inlet of the equipment is optimized using a nano-ceramic anti-sticking coating. The coating thickness is strictly controlled; actual testing shows that precise coating thickness can reduce the mineral powder adhesion rate from 15% to below 3%, greatly improving the flowability of the mineral powder material. Simultaneously, optimizing the tilt angle of the mineral powder conveying equipment increases conveying efficiency by 20%, effectively avoiding production interruptions caused by mineral powder accumulation and blockage, and ensuring continuous and stable operation of the grinding process. In addition, to reduce equipment wear and energy consumption, the grinding area of ​​the roller mill is equipped with a temperature monitoring sensor and an automatic lubrication system. When the temperature in the grinding area exceeds 80°C, the lubrication system is automatically activated to replenish the lubricant between the wear-resistant ceramic liner and the grinding media, thereby extending the service life of the equipment and maintaining stable powder particle size and production capacity.

[0038] Step 3: Roasting is carried out in the desulfurization furnace. The temperature and residence time in the main furnace reaction zone are strictly and precisely controlled. In the roasting desulfurization process, oxygen-enriched air is introduced and the flow rate is precisely controlled. The roasted mineral powder has a large specific surface area, and the dissolution rate is effectively improved.

[0039] Under specific production operating conditions, actual measurements showed: inorganic carbon removal rate of 42%, and mineral powder specific surface area of ​​365 m². 2 / g, the dissolution rate was effectively improved and the salt load of the downstream solution was reduced by 32%.

[0040] The roasting process is carried out in a desulfurization furnace, with strict and precise control over the temperature of the main furnace reaction zone and the residence time of the mineral powder. During the roasting desulfurization process, oxygen-enriched air is introduced, and its flow rate is precisely controlled. After this roasting treatment, a larger specific surface area of ​​the mineral powder is obtained, and the dissolution rate is effectively improved. In specific implementation, under specific conditions of main furnace reaction zone temperature and residence time, and with the introduction of oxygen-enriched air, the measured inorganic carbon removal rate, mineral powder specific surface area, and dissolution rate were all significantly improved, and the downstream solution desalination load was significantly reduced, effectively alleviating the processing burden of subsequent processes. To precisely control the roasting temperature and atmosphere, the desulfurization furnace is equipped with a zoned temperature control system and an online oxygen content monitoring device, which can adjust the fuel supply and oxygen-enriched air flow rate in real time according to the actual operating conditions inside the furnace, ensuring that the roasting process is always within the optimal process parameter range, guaranteeing the efficient removal of organic matter and inorganic carbon.

[0041] Step 4: Simultaneous removal of organic matter and inorganic carbon through high-temperature roasting, wherein the inorganic carbon removal rate is ≥40%, the salt discharge load of the downstream solution is reduced by 30%, and the moisture content of the mineral powder in Step 2 is ≤8%.

[0042] Specifically, by recovering waste heat from flue gas using specific equipment and high-temperature fans, the air entering the furnace is preheated to a certain temperature, significantly reducing energy consumption per ton of ore and greatly improving thermal efficiency. Under these process conditions, the inorganic carbon removal rate is ≥40%, the downstream solution salt discharge load is reduced by 30%, and the moisture content of the ore powder in step two is ≤8%. To reduce energy consumption, the system is equipped with specific equipment and high-temperature fans for flue gas waste heat recovery. Actual calculations show that this specific equipment and high-temperature fans can significantly increase the preheating temperature of the air entering the furnace, resulting in a substantial reduction in energy consumption per ton of ore, a significant increase in thermal efficiency, and a substantial improvement in energy utilization efficiency, thereby reducing production and operating costs. Simultaneously, to ensure stable quality of the roasted ore powder, the system is equipped with an online particle size analyzer and a chemical composition detection device to perform real-time sampling inspections of the roasted ore powder. Once deviations in particle size or composition are detected, the system immediately feeds back to the control system, automatically adjusting the roasting parameters to ensure the uniformity and reliability of product quality.

[0043] Example 2

[0044] Please see the appendix Figure 1 and attached Figure 2 A trihydrate bauxite organic matter roasting and removal system, comprising:

[0045] Mixing unit: equipped with a twin-helix agitator;

[0046] Dry grinding unit: a roller mill with wear-resistant ceramic liners, wherein an ultrasonic anti-clogging vibrator is installed at the discharge port of the dry grinding unit;

[0047] The roasting desulfurization unit is a three-stage temperature-controlled reactor with strict and precise temperature gradient control. The inner wall of the furnace of the roasting desulfurization unit is coated with silicon carbide.

[0048] Waste heat recovery unit: a specific device connected to the flue gas outlet and a high-temperature fan;

[0049] Specifically, the mixing unit is equipped with a twin-helix agitator with adjustable speed within a certain range. The twin-helix agitator employs a special helical blade design, with optimized blade spacing and inclination angle, effectively improving mixing efficiency and uniformity. In actual operation, strict control of speed and mixing time ensures a mixing uniformity of 98% (with an elemental distribution deviation of ≤2% as detected by XRF), guaranteeing the full integration of different types of bauxite and providing stable raw materials for subsequent processing. Furthermore, the mixing unit also features a raw material pre-drying device, utilizing waste heat recovered from subsequent processes to pre-dry the raw materials, further reducing the impact of raw material moisture content fluctuations on the entire process. The dry grinding unit uses a vertical roller mill with wear-resistant ceramic liners. An ultrasonic anti-clogging vibrator is installed at its discharge port, automatically starting and stopping once at a set time. The high-frequency vibration of the ultrasonic waves effectively breaks down the adhesion between mineral powder particles, preventing agglomeration and significantly increasing the material flow rate from 85% to 99%. Meanwhile, to adapt to production needs with different particle size requirements, the vertical roller mill is equipped with a variable frequency speed-regulating circulating fan and a classifier. By adjusting the fan speed and classifier speed, the particle size distribution of the finished mineral powder can be flexibly controlled, precisely adjusted within a specific range, and meets the differentiated particle size requirements of different subsequent processes. In addition, the grinding rollers and grinding discs of the dry grinding unit adopt a water cooling system to ensure the temperature stability of key components under high load operation, extend the equipment maintenance cycle, and ensure production continuity.

[0050] The roasting and desulfurization unit features a three-stage temperature control zone: a preheating zone where the moisture content of the mineral powder is reduced to below 1%; a reaction zone where organic matter begins to decompose rapidly; and an activation zone where inorganic carbon is deeply removed. A silicon carbide coating on the furnace inner wall increases the furnace wall's temperature resistance to 1000℃, extending its service life from 6 months to 18 months. Effective waste heat recovery from the flue gas is achieved by connecting to the flue gas outlet through specific equipment and a high-temperature fan. In actual operation, the heat exchanger significantly increases the temperature of the incoming air, significantly reducing fuel consumption and effectively improving thermal efficiency. Furthermore, the waste heat recovery unit is equipped with an intelligent control system that automatically adjusts the heat exchanger's operating status based on parameters such as flue gas temperature, flow rate, and incoming air demand, maximizing waste heat recovery efficiency. Simultaneously, to prevent ash accumulation and corrosion inside the heat exchanger, regular maintenance is performed using a combination of compressed air purging and chemical cleaning to ensure long-term stable and efficient operation.

[0051] Application scenario: An alumina plant processes imported Guinean trihydrate bauxite. After adopting this process, the annual ore processing capacity is 1 million tons, effectively removing organic matter; the back-end solution salt discharge load is reduced by 30%, effectively reducing the annual salt discharge and wastewater treatment costs.

[0052] The oxygen content of the flue gas is strictly controlled during the roasting process; the system is equipped with a CO concentration monitor, and the flue gas meets national emission standards after purification.

[0053] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A roasting and desorption process for organic matter in trihydrate bauxite, characterized in that, Includes the following steps: Step 1: Mix foreign trihydrate bauxite with domestic monohydrate gibbsite bauxite in a certain mass ratio. Step 2: Use a dry grinding process to produce mineral powder from the mixed ore in a final grinding equipment; Step 3: Roasting treatment is carried out in the desulfurization furnace, and the reaction zone of the main furnace is controlled according to specific temperature and residence time; Step 4: Simultaneously remove organic matter and inorganic carbon through high-temperature roasting.

2. The organic matter removal process for trihydrate bauxite by roasting according to claim 1, characterized in that, The feed inlet of the final grinding equipment is coated with a nano-ceramic anti-stick coating, and the tilt angle of the mineral powder conveying equipment is optimized.

3. The organic matter removal process for trihydrate bauxite by roasting according to claim 1, characterized in that, In the roasting desulfurization process, oxygen-enriched air is introduced, and the flow rate is strictly controlled.

4. The organic matter removal process for trihydrate bauxite by roasting according to claim 1, characterized in that, The organic matter removal efficiency satisfies the formula: n=1-e -k·t Where k = 0.0032T - 1.75 (T is the calcination temperature), t is the residence time (min), and η ≥ 75%.

5. A trihydrate bauxite organic matter roasting and removal system, using the trihydrate bauxite organic matter roasting and removal process as described in any one of claims 1-4, characterized in that, include: Mixing unit: equipped with a twin-helix agitator, speed 20-30 rpm; Dry milling unit: roller mill with wear-resistant ceramic liner; The roasting desulfurization unit consists of a three-stage temperature-controlled reactor to maintain a specific temperature gradient. Waste heat recovery unit: Waste heat is transported to the final grinding system via a high-temperature fan.

6. The organic matter roasting and removal system for trihydrate bauxite according to claim 5, characterized in that, The inner wall of the furnace chamber of the roasting furnace unit is coated with silicon carbide.

7. The organic matter roasting and removal system for trihydrate bauxite according to claim 5, characterized in that, An ultrasonic anti-clogging vibrator is installed at the discharge port of the dry powder making unit.

8. The organic matter removal process for trihydrate bauxite by roasting according to claim 1, characterized in that, The specific surface area of ​​the roasted mineral powder is ≥350m². 2 / g.

9. The organic matter removal process for trihydrate bauxite by roasting according to claim 1, characterized in that, The inorganic carbon removal rate is ≥40%, and the salt discharge load of the downstream solution is reduced by 30%.

10. The organic matter removal process for trihydrate bauxite by roasting according to claim 1, characterized in that, The moisture content of the mineral powder in step two is ≤8%.

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