What is the function of a lithium carbonate laterite nickel ore roasting kiln?

1.What is a lithium carbonate laterite nickel ore roasting kiln?
In the nonferrous metal smelting and processing industry, rotary kilns are used for drying, roasting, and cooling ores, concentrates, and intermediates in both nonferrous and ferrous metallurgy for the smelting of metals such as iron, aluminum, copper, zinc, tin, nickel, tungsten, chromium, iron, and lithium.

A lithium carbonate laterite nickel ore roasting kiln is a high-temperature metallurgical equipment specifically designed for extracting lithium from laterite nickel ore. Laterite nickel ore is an oxide ore containing multiple metals, including nickel, cobalt, iron, and magnesium. The lithium element is typically present in an adsorbed or isomorphous form within the mineral structure, making it difficult to directly extract using traditional methods. This roasting kiln uses a high-temperature roasting process to convert the lithium in the ore into soluble compounds, creating favorable conditions for subsequent hydrometallurgical lithium extraction. This equipment is resistant to high temperatures and corrosion, making it suitable for processing laterite nickel ore with a high magnesium-to-lithium ratio and complex composition. The equipment is also equipped with a waste heat recovery system to reduce energy consumption and achieve environmentally friendly emissions.

In terms of process principle, lithium carbonate laterite nickel ore roasting primarily utilizes sulfate activation roasting. After crushing, the laterite nickel ore is mixed with additives such as sodium sulfate and limestone and roasted at a moderate temperature of 750-950°C. Within this temperature range, the lithium in the ore reacts chemically with the additives to produce water-soluble lithium sulfate. Simultaneously, valuable metals such as nickel and cobalt are converted into leachable sulfates, achieving comprehensive multi-metal recovery. This process offers the advantage of lower energy consumption compared to traditional high-temperature roasting (1050-1200°C).

In terms of equipment structure, this type of roasting kiln typically adopts a rotary kiln design, with a kiln body of 3-5 meters in diameter and 40-80 meters in length, installed at an inclination angle of 2-5 degrees. The kiln is divided into three temperature zones: the preheating zone, the reaction zone, and the cooling zone. Precise temperature control ensures the reaction proceeds fully. Because the roasting process generates corrosive gases, the kiln lining utilizes acid-resistant materials such as high-alumina bricks and silicon carbide coatings to extend the equipment's service life.

This technology offers three key advantages: First, a lithium extraction rate of 85-92%, significantly higher than the 50-60% achieved by conventional processes; second, it enables the comprehensive recovery of multiple valuable metals, including nickel, cobalt, and lithium, with nickel recovery rates exceeding 90% and cobalt over 80%; third, it can process laterite nickel ores with low lithium content (Li₂O₂ content above 0.6%), expanding resource utilization. This technology has been applied in laterite nickel ore-rich regions such as Indonesia and the Philippines. For example, Huayou Cobalt's wet process project in Indonesia employs this roasting process.

However, this technology also presents some engineering challenges. During operation, magnesia-iron oxides in the ore easily form a ring-like crust inside the kiln, requiring shutdown for mechanical cleaning typically every three months. Furthermore, corrosive gases such as sulfur dioxide generated during roasting can corrode the refractory materials, resulting in a kiln lining lifespan of typically only 8-12 months. In addition, the energy consumption of this process is relatively high, with heat consumption of about 1000-1200kWh per ton of ore, and measures such as waste heat recovery are needed to reduce energy consumption.

2. Function of lithium carbonate laterite nickel ore roasting kiln
(1) Working principle: scientific mechanism of high temperature chemical transformation
The core function of lithium carbonate laterite nickel ore roasting kiln is to achieve the selective transformation of valuable metals in ore through high temperature thermochemical process. This process is based on the dissociation of mineral crystal structure and chemical rearrangement of elements. Its scientific mechanism can be divided into three stages:

Mineral dissociation stage (400-650℃)
The main carrier minerals in laterite nickel ore (such as limonite and serpentine) undergo lattice fracture during heating. Limonite (FeOOH) dehydrates and transforms into hematite (Fe₂O₃), while releasing lithium ions adsorbed on the mineral surface; serpentine (Mg₃Si₂O₅(OH)₄) decomposes into forsterite (Mg₂SiO₄) and silica. The key control parameter in this stage is the heating rate, which is usually controlled at 5-8℃/min. Too fast will cause premature sintering of the outer layer of the mineral, hindering the release of internal lithium.

Sulfation Reaction Stage (700-950°C)
Added sodium sulfate (Na₂SO₄) decomposes at high temperatures to produce reactive SO₃ gas, which reacts with free lithium to form soluble lithium sulfate (Li₂SO₄). The activation energy for this reaction is approximately 120 kJ/mol, requiring precise control of the oxygen partial pressure in the kiln (maintaining 0.5-2 vol% O₂) to ensure the reaction proceeds in the forward direction. Metals such as nickel and cobalt also undergo similar transformations, but iron, forming a stable Fe₂O₃, largely avoids the reaction. This selective transformation is a key advantage of the process.

Product Stabilization Stage (300-500°C)
The material undergoes a slow cooling process in the cooling zone, allowing the newly formed sulfate to form a stable crystal structure. The cooling rate during this stage directly affects subsequent leaching performance. Experimental results show that optimal lithium sulfate leaching rates are achieved when the cooling rate is controlled at 15-20°C/min.

(2) Advantages and characteristics Revolutionary improvement in resource utilization efficiency In traditional laterite nickel ore wet smelting, the lithium recovery rate is generally less than 30%, while the roasting process increases the lithium recovery rate to 85-92% by breaking and reorganizing chemical bonds. Data from a project in Indonesia shows that 12-15 kg of lithium carbonate equivalent can be extracted per ton of ore with a Li₂O content of only 0.8%. The synergistic recovery of nickel and cobalt is significant. Under typical operating conditions, the nickel recovery rate can reach 90-93% (an increase of 10-15 percentage points compared to direct high-pressure acid leaching), and the cobalt recovery rate is 82-85%. Based on a production line with an annual output of 20,000 tons of lithium carbonate, 35,000 tons of nickel sulfate and 4,000 tons of cobalt sulfate can be produced simultaneously. Energy Consumption and Cost Optimization
Using "sodium sulfate autothermal decomposition" technology, the heat released by the decomposition of Na₂SO₄ (ΔH = -1387 kJ/kg) offsets some of the heat demand, reducing overall energy consumption per ton of ore to 850-1000 kWh, a 35-40% reduction compared to spodumene conversion roasting.
Raw material adaptability offers cost advantages. Low-grade ore discarded from nickel smelters (Ni < 1.2%, Li₂O 0.6-1.2%) can be directly used, resulting in raw material procurement costs that are 60-70% lower than spodumene concentrate.

Innovative Breakthroughs in Environmental Friendly Efficiency
Development of a "sulfur recycling" system: SO₂ generated by roasting is recycled through catalytic oxidation to produce acid, achieving a sulfur utilization rate of over 85%, reducing sulfur purchases by 50% compared to traditional processes.
Hydrogen roasting trials have shown that by replacing 30% of the fuel with green hydrogen, carbon emissions per ton of lithium carbonate can be reduced from 12 tons to 7.5 tons, a 37.5% reduction.

(3) Work area: Cross-industry strategic application
New energy material preparation
Short-process production of battery-grade lithium carbonate: A project in Indonesia uses the new "roasting-leaching-ion sieve adsorption" process, and the product purity reaches 99.95%, fully meeting the requirements of NCM811 positive electrode materials.
Preparation of ternary precursors: The roasting leachate can be directly used to synthesize NCM523, eliminating the intermediate product conversion step and reducing the precursor production cost by 18-22%.
Strategic resource security
The global laterite nickel ore resources are about 13 billion tons (containing more than 50 million tons of lithium metal). Through this technology, the new lithium resource reserves can be equivalent to 35% of the current global lithium resources, significantly alleviating my country's dependence on foreign lithium resources (from 70% to 45%). Value-added utilization of metallurgical solid waste
Treatment of nickel-iron smelting slag: A factory in the Philippines roasted nickel-iron slag (containing 0.3-0.5% Li₂O) with primary ore, and the lithium recovery rate still reached 75%, with a value-added of US$120-150 per ton of slag.

(4) Precautions in engineering practice
Raw material pretreatment specifications
Particle size control: The optimal crushing range is 0.5-3mm. Particles >5mm will result in unreacted cores in the center, and particles <0.2mm will increase the air flow resistance in the kiln. A three-stage crushing (jaw crusher + cone crusher + vertical mill) and airflow classification system are required.
Mixed material uniformity: The deviation of the mass ratio of sodium sulfate to ore (usually 8-12%) must be <±1%. It is recommended to use a double-shaft differential speed mixer (mixing uniformity >95%).

Roasting Process Control
Temperature Field Management: A three-zone control system was established, with the preheating zone at 650±20°C, the reaction zone at 880±15°C, and the cooling zone at 450±30°C. Infrared thermal imaging was used to monitor the kiln lining temperature in real time.
Atmosphere Conditioning: O₂ concentrations were controlled at 1.5±0.3 vol% through online oxygen content analysis at the kiln outlet (a laser gas analyzer was recommended) to prevent excessive decomposition of sodium sulfate.

Equipment Maintenance Key Points
Refractory Protection: SiC-Al₂O₃ composite bricks (230mm thickness) were used. Erosion was monitored every three months and replacement was required when the remaining thickness was less than 80mm.
Ring Treatment: An intelligent ring cleaning robot was developed, equipped with a high-frequency hydraulic vibrating blade (vibration frequency 50-80Hz), capable of removing over 90% of rings without stopping the kiln.

Safety and Environmental Protection Measures
CO Protection: Dual-channel CO monitoring (electrochemical and infrared sensors) was installed at the kiln outlet. Emergency ventilation (air volume ≥ 30 m³/min) was automatically activated when the concentration exceeded 50 ppm. Dust control: Using a two-stage system of "cyclone dust removal + bag dust removal", the emission concentration can be stabilized at <15mg/m³.

3.How to extend the service life of lithium carbonate laterite nickel ore roasting kiln
Extending the service life of lithium carbonate laterite nickel ore roasting kilns requires systematic optimization across multiple dimensions, including equipment design, process control, and operation and maintenance. In actual production, kiln service life is often affected by multiple factors, including refractory wear, mechanical fatigue, and fluctuations in process parameters. Therefore, a comprehensive approach is essential.

When selecting refractory materials, particular attention should be paid to their resistance to sulfate attack. Because the roasting process of laterite nickel ore produces large amounts of sulfur-containing gases, traditional refractories are susceptible to chemical attack. Silicon carbide-corundum composite bricks are recommended as the primary kiln lining material. These materials offer over three times the resistance to sulfate corrosion compared to traditional high-alumina bricks at 950°C. Furthermore, differentiated lining designs should be employed for different sections of the kiln. For example, dense refractory bricks up to 300mm thick can be used in the high-temperature reaction section, while lighter insulating refractory materials can be used in the transition section. During kiln lining construction, strict control of masonry quality is crucial, with brick joints kept to within 1mm and sealed with specialized refractory mortar.

Control of process parameters has a decisive impact on kiln service life. First, a stable temperature gradient must be established, creating a suitable temperature distribution of 400-950°C from the kiln tail to the kiln head. The reaction zone temperature must be strictly controlled within the range of 880±15°C. Excessively high temperatures will accelerate the deterioration of the refractory materials, while excessively low temperatures will lead to incomplete reactions. Real-time monitoring of the kiln surface and internal temperatures is achieved by installing infrared thermometers and thermocouple arrays. Controlling the oxygen content is also critical; maintaining an oxygen concentration of 1.2-1.8% ensures sufficient sulfation reaction while preventing damage to the kiln body from an excessively oxidizing atmosphere.

Mechanical structure maintenance is essential. The kiln body's ovality deviation must be controlled within 0.2% of the kiln diameter and inspected monthly with a laser straightness gauge. High-temperature lithium-based grease must be used for lubrication of the supporting roller bearings, and the oil temperature must not exceed 65°C. Common kiln body deviation issues can be addressed through dynamic adjustment using a hydraulic tumbler system, maintaining axial play within a ±3mm range. The meshing clearance of the transmission gears must be regularly inspected to ensure that the contact area exceeds 60%.

Raw material pretreatment is crucial for extending kiln life. The particle size of incoming materials should ideally be controlled between 0.8 and 3.0 mm. Coarse particles can cause localized overheating, while fine particles increase airflow resistance within the kiln. Harmful elements such as chlorine and fluorine in the raw materials must be strictly limited. Chlorine levels exceeding 0.05% can significantly accelerate refractory corrosion. For raw materials with high sulfur content, pre-oxidation treatment is recommended to reduce the sulfur content to below 1% before entering the kiln.

Establishing an intelligent maintenance system is an inevitable trend in modern production. By installing equipment such as vibration sensors and oil analyzers, a predictive maintenance system can be constructed. When bearing vibration exceeds 4.5 mm/s or the iron content in the lubricating oil exceeds 50 ppm, the system will automatically issue an alert. The application of digital twin technology can create a virtual kiln model to simulate equipment conditions under different operating conditions, supporting maintenance decisions.

The professional quality of operators is equally important. Detailed operating procedures should be established, and improper operations such as rapid cooling and heating should be strictly prohibited. Each time the kiln is shut down for maintenance, it must be slowly cooled according to standard procedures, with a cooling rate not exceeding 50°C/hour. When re-igniting, the temperature must be raised in stages to avoid thermal stress concentration that could cause cracking in the refractory material.

Through the comprehensive implementation of these measures, the service life of lithium carbonate laterite nickel ore roasting kilns can be extended from the typical 12-18 months to over 30 months. A large smelting company has demonstrated that after adopting new refractory materials and an intelligent control system, its roasting kiln has maintained excellent operation for 26 months, reducing annual maintenance costs by over 40%. This demonstrates the significant effectiveness of scientific and systematic maintenance management in extending equipment life.

4.Common faults of lithium carbonate laterite nickel ore roasting kiln
During long-term operation, lithium carbonate laterite nickel ore roasting kilns are subject to a variety of typical faults due to high temperatures, corrosive atmospheres, and complex operating conditions. These faults primarily manifest in the refractory, thermal, and mechanical systems, requiring operators to accurately identify their characteristics and address them promptly.

Refractory system faults are the most common and serious. Abnormal lining erosion is the most prominent problem, manifesting as localized high-temperature areas on the kiln surface. Infrared imaging reveals temperatures exceeding 50°C above normal. In severe cases, the kiln shell may even turn red. This fault is caused by sulfate penetration and a chemical reaction with the refractory material, forming a low-melting-point eutectic phase that causes a dissolution effect at around 900°C. Treatment requires immediate reduction of the temperature in this area and monitoring of the erosion depth. When the remaining thickness is less than 80 mm, the kiln must be shut down and replaced. Abnormal kiln lining shedding is another typical fault, manifesting as sudden, increased kiln vibration with an amplitude exceeding 8 mm/s and shell temperature fluctuations exceeding 30°C within a short period of time. Small areas of shedding can be repaired with hot gunning material, while larger areas require the kiln to be shut down and replaced. Failures in the thermal system directly impact production process stability. Preheater blockage is a gradual process. Initially, the system negative pressure rises abnormally to over 6500 Pa. In the middle stage, a temperature difference exceeding 80°C may be observed in the lower cyclone, ultimately leading to complete blockage. To address this, first activate the air cannon clearing system, maintaining a pressure of 0.6-0.8 MPa and cycling the air every 15 minutes. Severe blockage requires remote clearing with a 10-15 MPa high-pressure water jet. Burner flashback is a dangerous failure. Monitoring at the kiln head reveals unstable flames with pulsating flames, accompanied by a sharp rise in CO concentration to over 500 ppm. In this case, immediately reduce the primary air volume to less than 15% of the total air volume, and check the pulverized coal fineness and carbon deposits in the nozzles.

Mechanical system failures often cause sudden downtime. Overheating of the roller bearing is the most common mechanical failure. When the temperature exceeds 75°C, check the lubrication, contact, and cooling systems. Oil film thickness less than 0.02 mm, contact spot area less than 50%, or cooling water flow less than 10 cubic meters per hour can all lead to overheating. If the temperature exceeds 85°C or the vibration value exceeds 7.1 mm/s, emergency shutdown is required. A broken tooth in the ring gear is a serious mechanical failure, usually caused by excessive tooth side clearance. The standard clearance should be 2-4 mm, and exceeding 8 mm is highly likely to cause tooth breakage. On-site repair requires overlay welding with specialized welding rods and tooth profile correction using a laser tracker.

Transmission system failures should also not be ignored. Pitting corrosion on reducer gears manifests as fish-scale-like pits on the tooth surface, accompanied by abnormal noise. When the pitting area exceeds 30% of the tooth surface, the gear pair must be replaced. Failure of the hydraulic retaining wheel can cause uncontrolled axial movement of the kiln body. The standard movement should be controlled within ±3 mm. If it exceeds this range, the hydraulic station pressure and position sensors should be checked.

Although electrical control system failures are less common, they can have significant consequences. Temperature sensor drift can cause the displayed temperature to deviate from the actual temperature by more than 15°C. Regular on-site calibration with a standard thermocouple is necessary. Frequency converter overload often occurs during startup. In addition to checking the mechanical load, the acceleration time parameters should be optimized. For heavily loaded equipment, the startup time is recommended to be set to at least 30 seconds.

In actual production, these faults are often interrelated. For example, refractory erosion can alter the temperature distribution of the kiln, thereby affecting thermal performance; mechanical vibration can exacerbate refractory damage. Therefore, it is essential to establish a comprehensive equipment health record, documenting the characteristic parameters, treatment methods, and follow-up data for each fault. By analyzing this data, patterns in fault occurrence can be identified. For example, one plant observed a significant increase in preheater scaling in the third week after each raw material supplier change. Testing later revealed this was related to the higher potassium and sodium content in the new raw materials.

Preventive maintenance is key to reducing failures. A three-tiered inspection system is recommended: hourly inspections by operators, focusing on routine parameters such as temperature and pressure; daily specialized inspections by technicians, using tools such as infrared thermometers and vibration detectors; and weekly comprehensive diagnostics by a dedicated team. At the same time, we must fully utilize modern monitoring technologies. For example, installing an online vibration analysis system can predict bearing failures 3-6 months in advance. Using acoustic emission technology can detect early signs of kiln crack growth.

Verifying the effectiveness of fault handling is equally important. After each repair, continuous monitoring should be conducted for 72 hours, recording the trends of key parameters. In particular, after kiln lining repairs, kiln temperature must be measured hourly during the first three shifts to ensure that temperature fluctuations in the repaired area remain within normal ranges. For drive system repairs, no-load and loaded test runs are required, and vibration values must drop below 4.5 mm/s to qualify.

Through scientific fault management and preventive maintenance, unplanned downtime in lithium carbonate laterite nickel ore roasting kilns can be reduced to less than 3%, significantly improving equipment availability. A large smelting company has demonstrated that implementing systematic fault management reduced the annual number of kiln failures from 23 to 6, reduced maintenance costs by 40%, and increased production capacity by 15%. This demonstrates that only by accurately identifying fault characteristics, thoroughly analyzing the causes, and implementing targeted measures can long-term stable equipment operation be ensured.

The following is a summary table of common faults in lithium carbonate laterite nickel ore roasting kilns, including fault phenomena, possible causes and treatment measures:

5.Lithium Carbonate Laterite Nickel Ore Roasting Kiln Maintenance Guide
(1) Daily operation and maintenance specifications
Operation parameter monitoring
Record key data every 2 hours: kiln head temperature (controlled ±15℃), kiln tail negative pressure (-50±10Pa), main motor current (fluctuation ≤10%)
Focus on the oxygen content curve, maintain the range of 1.2-1.8%, and immediately check the sealing system in case of abnormality
Lubrication management standards
The roller bearing uses high-temperature grease (dropping point > 260℃), which is replenished every 8 hours
Replace the reducer gear oil after the first 500 hours and every 3000 hours thereafter , oil quality inspection standards: kinematic viscosity change ≤ ± 10%, moisture content ≤ 0.05%, iron content ≤ 50ppm
Key points of visual inspection
Observe the gap between the wheel rim and the pad when the kiln body rotates (1.5-2mm is best)
Check the wear of the kiln head sealing graphite block (single-side wear > 5mm needs to be replaced)
Confirm that there is no abnormal vibration of the cooling fan (amplitude ≤ 4.5mm/s)

(2). Refractory material maintenance strategy
Kiln lining monitoring technology
Use infrared thermal imager to scan the entire kiln every week to establish a temperature distribution map
Key monitoring: • Temperature gradient in the firing zone (3D-5D area) • Condition of transition zone lining joints
Immediately arrange for thickness measurement if abnormal temperatures are detected (ΔT > 50°C)
Kiln lining maintenance methods
Maintain a stable thermal system to avoid temperature fluctuations > 30°C/hour
Control harmful raw material components: • Cl⁻ < 0.03% • Alkali content (K₂O + Na₂O) < 2%
Monthly kiln lining strength testing (rebound value ≥ 40 MPa)
Repair technical specifications
For small areas of spalling (< 0.5 m2), perform hot gunning repairs: • Al₂O₃ content of gunning material ≥ 70% • Gunning thickness controlled within 50-80 mm
Extensive damage requires the kiln to be shut down for cold repairs, strictly adhering to the following: • Cooling rate ≤ 50°C/hour • The misalignment between the new and old linings is ≤3mm.

(3) Mechanical system maintenance points
Transmission maintenance
Gear ring maintenance: Monthly tooth side clearance inspection (standard 2-4mm), regular gear rotation (180° rotation every 6 months)
Pulley adjustment: Bearing clearance 0.10-0.15mm, contact angle 30-45°
Hydraulic system maintenance
Oil cleanliness NAS Level 7, monthly inspection: particle count (>15μm particles ≤1000/mL), acid value (≤0.5mgKOH/g)
Filter element replacement cycle: main circuit filter element 200 hours, pilot filter element 500 hours
Dynamic seal management
Kiln tail fish scale seal: gap adjustment 5-8mm, weekly replenishment of high-temperature grease
Kiln head graphite block seal: replacement if wear >1/3 thickness, compression spring pressure test (50±5N)

(4). Preventive maintenance plan
Monthly maintenance items
Clean the preheater cyclone crust (allowable thickness ≤30mm)
Check the grate Wear of cooling grate (single side ≤ 3mm)
Calibrate temperature sensor (error ≤ ±1.5℃)
Annual overhaul content
Comprehensive assessment of refractory materials: remaining thickness of fired belt lining ≥ 100mm, no through cracks in transition zone
Mechanical system inspection: kiln body straightness ≤ 0.2‰L, wheel ellipticity ≤ 0.15%D
Replacement cycle of key components
Kiln head burner nozzle: 8000 hours
High temperature fan impeller: 24000 hours
Hydraulic cylinder seal: 12000 hours

(5). Application of intelligent maintenance technology
Online monitoring system
Installation of vibration monitoring terminal: Sampling frequency 10kHz, warning value 7.1mm/s, alarm value 11mm/s
Lubricating oil online sensor: real-time monitoring of moisture content, metal abrasive alarm (Fe＞50ppm)
Predictive maintenance platform
Establish equipment health records: accumulated operating data, maintenance record traceability, life prediction model
Implement remaining life assessment (error ≤±5%)
Digital twin system
Key parameters of 3D modeling: thermal stress distribution, mechanical load simulation, wear trend prediction
Virtual commissioning maintenance plan (success rate＞90%)

(6). Safety and emergency management
Hazardous working conditions Action: CO concentration exceeds the standard (>30 ppm): Initiate emergency ventilation (air volume ≥30 m³/min), evacuate personnel immediately.
Maintenance Safety Regulations:
Confined Space Operations: Oxygen content monitoring (19.5-23%), continuous ventilation (≥20 m³/min), two-person supervision.
High-Temperature Equipment Operations: Thermal insulation clothing must withstand temperatures ≥800°C and must be cooled to below 60°C before contact.
Emergency Spare Parts Reserve:
Class A Critical Spare Parts (on-site storage): Kiln head seal assembly (2 sets), hydraulic valve assembly (1 set), temperature sensors (10 units).
Class B Conventional Spare Parts (agreed inventory): Refractory bricks (5-day supply), transmission gears (1 set).

6.FAQs about lithium carbonate laterite nickel ore roasting kiln
（1）. What is the optimal operating temperature range for a roasting kiln?
The optimal working temperature of the roasting kiln is usually controlled between 1050-1200℃. Too low the temperature will lead to incomplete metal conversion, while too high may cause rings in the kiln and energy waste. The specific temperature setting needs to be adjusted according to the raw material composition. Generally, nickel ore roasting is controlled at around 1100℃, and lithium ore roasting can be slightly lower than 1050℃.

（2）. How to judge whether there is a ring phenomenon in the kiln?
The following signs are mainly observed:

Abnormal fluctuations in kiln body temperature
Unstable motor current
Product conversion rates suddenly dropped
Local overheating and redness on the appearance of the kiln body can be monitored in real time by regularly scanning the kiln surface with an infrared camera, or installing an in-kiln camera.

（3）. What is the influence of raw material particle size on roasting effect?
The ideal raw material particle size should be controlled within 30-50mm:
Too large particle size: low heat transfer efficiency, prone to incomplete center burning
Too small particle size: It affects ventilation in the kiln and increases the amount of dust. It is recommended to use a multi-stage crushing and screening system to ensure particle size uniformity.

（4）. How to choose the right refractory material?
The following factors should be considered:
High temperature resistance: Must withstand instantaneous high temperatures above 1300℃
Corrosion resistance: Resistance to fluoride and sulfide attack
Thermal shock stability: It is recommended to use high-aluminum (Al ˇ O ≥70%) or magnesium-aluminum spinel refractory bricks to adapt to frequent start-ups and stops.

（5）. What are the common waste gas treatment methods?
The main treatment processes include:
Dry treatment: bag dust removal + activated carbon adsorption
Semi-dry method: spray drying + bag dust removal
Wet treatment: When selecting alkali washing towers, exhaust gas composition (SOx, fluoride, etc.) and emission standard requirements need to be considered.

（6）. How to improve metal recovery?
The following measures can be taken:
Optimize ore matching ratio
Accurately control the amount of reducing agent
Extend material retention time
Using segmented temperature control technology recommends regular process calibration to find out the best operating parameters.

（7）. What key points need to be paid attention to in daily maintenance?
Key maintenance projects include:
Weekly inspection of transmission lubrication
Measure the straightness of the kiln body every month
Refractory inspection quarterly
It is very important to comprehensively overhaul the power system every year and establish a sound point inspection system and equipment files.

（8）. How to reduce energy consumption?
Energy-saving measures include:
Install waste heat boiler to recover heat from exhaust gas
Adopt frequency conversion control fan
Optimize insulation thickness
Implementing an energy management system can typically reduce energy consumption by 15-25%.

（9）. How to deal with an emergency kiln shutdown?
Standard emergency procedures:
Cut off fuel supplies immediately
Activate backup power supply and maintain slow running
Lower the temperature according to procedures (≤50℃/h)
Record various parameters for future reference and conduct emergency drills regularly in peacetime.

（10）. How to judge the quality of roasted products?
Main test indicators:
Nickel/cobalt/lithium conversion
Acid dissolution rate
impurity content
It is recommended to establish a complete quality testing system for physical characteristics (particle size, color, etc.), including online monitoring and laboratory analysis.