Rotary Kiln Research Articles

Multi-objective optimization of clean utilization for zinc leaching residues by rotary kiln using neural network coupled modeling

Aiming at the complicated problems of green and high efficiency recovery for metal zinc in the process of resource utilization for zinc leaching residues by rotary kiln，it is crucial to optimize the zinc volatilization efficiency (VEZn) with minimizing the emission intensity of CO2 (EICO2) and kiln slag (EIks). A quantitative regulation approach of key parameters coupled with neural network simulations and multi-objective optimization algorithm is proposed in this study. The index prediction models of VEZn, EICO2 and EIks have been established through the back propagation neural network (BP-NNP) and its two improved algorithm, respectively. Through training by long time series of actual operating data, the results showed that the BP-NNP model improved by particle swarm optimization (PSO) could more accurately describe the complex nonlinear mapping relationship between wide fluctuating parameters and VEZn, EICO2 and EIks, and the mean absolute percentage errors (MAPE) could be reduced to 6.00 × 10−3, 8.52 × 10−3 and 6.08 × 10−2, respectively. Furthermore, the developed index prediction model was incorporated into cuckoo search (CS) and non-dominated sorting genetic algorithm-II (NSGA-Ⅱ) that performed Pareto dominance-based multi-objective optimization. In experiments conducted, the significant advantages of NSGA-Ⅱ were revealed that the corresponding Pareto-optimal solutions with VEZn distribution between 93.32% and 94.52% were obtained. Meanwhile, EICO2 and EIks could be reduced to 1.525 t/t and 0.317 t/t, respectively. And comprehensive benefits by Pareto-optimal solutions were analyzed to provide various representative countermeasures to assist decision-makers. New insights gained herein could enable clean, efficient and low-carbon process regulations for recycling of solid waste in zinc hydrometallurgy industry.

Evaluating rotary and static calcination processes for montmorillonite marl: Pozzolanic properties, compressive strength, and cementitious paste characteristics

Marls, widely available globally, are under research as supplementary cementitious materials. This study investigated metamontmorillonite reactivity and optimal calcination temperatures. The complex composition of marls, including minerals like montmorillonite and dolomite alongside chemical oxides such as CaO and MgO, posed challenges in determining the ideal calcination temperature. Material transformations at varying temperatures were tracked using X-ray diffraction, scanning electron microscopy, and nuclear magnetic resonance techniques. Comparative analysis of static and rotary kilns evaluated mortar compressive strength after 28 days, determining suitable replacement levels and the best calcination temperature. The study determined that calcination at 850 °C maximized pozzolanic reactivity, resulting in the formation of β-C2S. Static furnace calcination showed a slight advantage over rotary kiln. Mortar with 30% calcined marl replacement at water: binder ratio (W/B = 0.45) exhibited the highest compressive strength. Hydration analysis revealed the formation of calcium carboaluminate and hydrotalcite hydrates, with Al/Si = 0.18 composition.

Research of Reactions on Ferronickel Laterite by Rotary Kiln Furnace Process

Nickel is an important strategic metal, which is mainly used for the production of a wide range in the production of various anti-corrosion steels. Electric furnace, rotary kiln and smelting is currently the world-wide integration process for the production of ferronickel from nickel laterite ore, despite its high energy consumption. In this study, with the aim of providing some meaningful analysis for the production of ferronickel and reactions formed in the rotary kiln. The samples obtained were analyzed under conditions including reducing parameters (temperature and time) and smelting parameters (CaO, Al2O3 and MgO ratios). The metal content as well as the Ni, Fe, S and P content of ferronickel were taken into account. The results showed that Ni-containing ferronickel from a laterite with 0.88 wt. % Ni during the process in the rotating furnace is characterized by different reactions which have been verified by XRD diffraction.

Effect of momentum flow ratio on entrainment of a confined coaxial jet in a co-flow

Iron ore pellet production processes produce large amounts of CO2 emissions when burning fossil fuels. One example is the grate-kiln process, where normally a coal flame is used to indurate pellets. To mitigate the emissions, coal used in rotary kilns can be replaced with for example hydrogen. However, the fuel is mixed with secondary process air, and replacing a solid fuel with a gaseous one changes the mixing characteristics. This demands different means of injecting the fuel. A coaxial jet can be used to control the mixing of fuel and secondary air, as well as the flow field. The aim is to control the mixing of hydrogen and secondary air to achieve a hydrogen flame that is similar to the reference coal flame. This study numerically investigates different coaxial jet configurations. Steady-state simulations of a simplified model of the real kiln are performed using a Reynolds Stress turbulence model. Results show that decreasing the momentum flow ratio between the outer and inner jet, M jet , to a certain value delays the spread of the hydrogen jet and thus gives a longer jet. Further decreasing this ratio gives an even longer jet, but has the side effect of producing recirculation of hydrogen.

Decarbonizing rotary kiln–induction furnace based sponge iron production

The direct carbon dioxide (CO2) emissions from the iron and steel sector are nearly 7 % of the global CO2 emissions from energy use. India is the world's second-largest producer of steel and the largest sponge iron producer. India produces one-third of the global sponge iron, mostly from rotary kilns using coal as an energy source, resulting in higher energy and emission intensities than the global average. This study evaluates major options for CO2 abatement in the rotary kiln–induction furnace process for steel production. Based on the mass and energy balances of a typical sponge iron plant, this study evaluates the techno-economic potential of nine major decarbonization measures. The proposed decarbonization measures include improved energy efficiency, improved material efficiency, renewable energy use, and fuel substitution. Marginal abatement and green premium curves are generated by incorporating the dependency of different measures. Depending upon the set of options chosen, carbon abatement is in the range of 55.8 %–99.2 %. It is observed that 11.5 %–20.6 % of decarbonization potential can be achieved without any additional cost to the customer. These findings are insightful for policymakers and industry stakeholders and provide a foundation for designing and implementing a net-zero pathway for the sector.

Investigation of the Waelz oxide calcination process in tubular rotary kilns

Investigation of the Waelz oxide calcination process in tubular rotary kilns

Smoothed particle hydrodynamics simulation of transient heat transfer within rotary kiln

Rotary kilns are widely used in industries to heat or cool various materials. Previously the heat efficiency of rotary kiln is often evaluated by assuming the temperature is uniformly distributed within the particle bed, while lacking insights into the recirculating particle flows and the resulted non-uniform heat transfer. Here a smoothed particle hydrodynamics (SPH) approach is deployed to study the particle flow and particle–particle, particle–wall heat transfer in the rotary kilns. The results reveal that there exist low-temperature regimes in the core of rotary kilns depending on the filling levels. The temperature distribution is thus nonuniform and closely related to the particle flow pattern. In terms of heating efficiency, the thermal conductivity of particles exerts the greatest influence on the total heat transfer in rotary kiln. Other material and operational parameters, including the rotating speed, filling level, thermal load, and internal friction of particles, also remarkably affect the heat transfer according to the present simulation results, which are of significance to optimize the heating efficiency of rotary kiln.

COMPARATIVE ANALYSIS OF ENERGY EFFICIENCY OF THERMAL OPERATION OF ROTARY KILNS WITH DIFFERENT HEATING SYSTEMS

Analysis of the design features of known heating systems for large rotary kilns and modern methods of influencing the formation of the flame and the distribution of the temperature profile is presented. It has been established that most of the known methods of forming the flame and temperature profile of the working space of rotary kilns are based on methods of influencing air flows, in particular secondary air, the share of which in the total volume of combustion air is 70–100 %. On the basis of previous studies and observations, it is proposed to form a flame using additional sideways gas jets from the burner. Examples of modernization of heating systems of existing industrial rotary kilns for firing various materials, including ferronickel ore, fireclay, and lime, are presented. After installing burners with controlled flame parameters and changing the design of the combustion air supply system in the working space of the kilns, an optimal temperature distribution along their length was obtained. It was determined that the required temperature at about half the length of the kilns is almost constant, without significant fluctuations, differing at the beginning and end of the firing zone by 30–70 °C. The decrease in the temperature of the exhaust gases from the kilns after the modernization of the heating systems indicates an intensification of heat exchange in the workspace, which leads to a decrease in specific fuel consumption by 7–15 %, as well as an improvement in the quality of the final material. A comparative analysis of the thermal efficiency of operating rotary kilns depending on the design features of the heating system is presented. Bibl. 24, Fig. 4.

Evaluation and Analysis of Cement Raw Meal Homogenization Characteristics Based on Simulated Equipment Models.

In recent years, the variability in the composition of cement raw materials has increasingly impacted the quality of cement products. However, there has been relatively little research on the homogenization effects of equipment in the cement production process. Existing studies mainly focus on the primary functions of equipment, such as the grinding efficiency of ball mills, the thermal decomposition in cyclone preheaters, and the thermal decomposition in rotary kilns. This study selected four typical pieces of equipment with significant homogenization functions for an in-depth investigation: ball mills, pneumatic homogenizing silos, cyclone preheaters, and rotary kilns. To assess the homogenization efficacy of each apparatus, scaled-down models of these devices were constructed and subjected to simulated experiments. To improve experimental efficiency and realistically simulate actual production conditions in a laboratory setting, this study used the uniformity of the electrical capacitance of mixed powders instead of compositional uniformity to analyze homogenization effects. The test material in the experiment consisted of a mixture of raw meal from a cement factory with a high dielectric constant and Fe3O4 powder. The parallel plate capacitance method was employed to ascertain the capacitance value of the mixed powder prior to and subsequent to treatment by each equipment model. The fluctuation of the input and output curves was analyzed, and the standard deviation (S), coefficient of variation (R), and homogenization multiplier (H) were calculated in order to evaluate the homogenization effect of each equipment model on the raw meal. The findings of the study indicated that the pneumatic homogenizer exhibited an exemplary homogenization effect, followed by the ball mill. For the ball mill, a higher proportion of small balls in the gradation can significantly enhance the homogenization effect without considering the grinding efficiency. The five-stage cyclone preheater also has a better homogenization effect, while the rotary kiln has a less significant homogenization effect on raw meal. Finally, the raw meal processed by each equipment model was used for clinker calcination and the preparation of cement mortar samples. After curing for three days, the compressive and flexural strengths of the samples were tested, thereby indirectly verifying the homogenization effect of each equipment model on the raw meal. This study helps to understand the homogenization process of raw materials by equipment in cement production and provides certain reference and data support for equipment selection, operation optimization, and quality control in the cement production process.

Effect of oxy-fuel combustion with different O2/CO2 fractions on the pulverized coal combustion mechanism and heat transfer characteristics in rotary kilns: A numerical simulation study

Oxy-fuel combustion combined with carbon capture and storage is the most effective and direct technology to achieve carbon neutrality in cement industry. In this work, numerical simulation was employed to investigate the effects of air combustion and oxy-fuel combustion with different O2/CO2 fractions on the airflow field, temperature field, pulverized coal combustion mechanism, heat transfer characteristics and NOx distribution in rotary kiln. The results show that the airflow field under different conditions has no significant change. When transitioning from the air condition to the oxy-fuel condition, the ignition point of pulverized coal extends backward by approximately 0.2 m. The maximum temperature decreases from 2306 K to 2052 K, and the temperature becomes more uniform. As the oxygen concentration in the primary air increases, both the maximum and average temperatures gradually rise, and the flame length shortens from 25.4 m to 24.16 m. In the rotary kiln, the locations of char oxidation and gasification reactions differ, but these reaction locations remain consistent under different conditions. Under oxy-fuel conditions, the oxidation rate and oxidation proportion of char decrease, while the gasification rate and gasification proportion of char increase, resulting in a shortening of the burnout distance of coal from 34.5 m to 31.3 m. With increasing oxygen concentration in the primary air, the rates of char oxidation and gasification gradually rise, further shortening the burnout distance. The decrease in temperature at the front end of the rotary kiln under oxy-fuel conditions reduces the total heat transfer in the burning zone by 15 %. When the oxygen content of the primary air is 70 %, it ensures stable calcination of clinker. Additionally, under oxy-fuel conditions, the NOx generation is significantly reduced. With the increase of oxygen concentration in the primary air, the NOx concentration at the outlet decreases slightly from 451 ppm to 406 ppm, due to the increase in kiln temperature that favors the reduction of fuel NOx.

Lowering carbon emissions from a zinc oxide rotary kiln using event-scheduling observer-based economic model predictive controller

Background:The leading carbon emitting unit of the zinc smelting industry is the zinc oxide rotary kiln, which preserves a trade-off between carbothermic reduction and the zinc recovery rate. To scale up a substantial zinc restoration rate during the hydrometallurgical process, a substantial amount of coke is combusted, which leads to significant greenhouse gas emissions. It is imperative to mitigate the emission of carbon as reduced as possible. Since the kiln operates in three different regions — gas, solid, and wall — several highly non-uniform paths are typically linked to one another to yield complex looping processes. In industrial settings, solid maldistribution and gas refluxing pose prevalent challenges in the gas–solid flow mechanism. Consequently, control over processes and observation of the internal states/concomitant parameters become critical for ensuring safe and reliable operation. Therefore, it is imperative to devise effective control layouts to optimize the functioning of the kiln system. Method:(i) The usual form of model-predictive control rule is paired with an economic stage cost (using the CasADi optimization method) to offer optimal consumption of the coal and the rotation speed, thereby effectively alleviating the adverse effects of the unmeasured perturbations, actuator faults, or multi-sensor failures. (ii) With the aid of accessible state sensors, a cubature Kalman filter infused with a singular-value-decomposition strategy reliably predicts uncertainties/faults of the actuators or the unmeasured states of the kiln. (iii) cubature Kalman filter and event-triggered scheduling are utilized together, to consume less communication resources. Significant findings:A variety of indicators, such as zinc recovery rate (1.35% improvement), carbon emissivity (11.54% improvement), residence time (6% shorter), accuracy of the controllers/observers were well assessed and compared with standard form of the non-linear model predictive control law to figure out the efficiency and acceptability of the economic model predictive controller, demonstrating on an industrial rotary kiln. An in-depth study of the proposed control method satisfying Lyapunov inequality has been addressed.

Operation optimization of cement clinker production line based on neural network and genetic algorithm

The operation control plays a great role in the running performance of an industrial process. To achieve a successful control, the key point is searching for the target value of the control parameters. The relationship between operation parameters and performance parameters is usually nonlinear and complex, so it is hard to control an industrial process excellently with workers' experience. Based on a large amount of actual operation data, a bridge between control parameters and performance parameters might be built by the neural network. Prediction model is established by using neural network, genetic algorithm was then used to refine these parameters, the optimal condition can be further achieved by combining the relation bridge and genetic algorithm (GA). Paying attention to a cement clinker production process, this article established an optimizing approach based on the neural network and genetic algorithm and one-year operation data (615 sets). The feeding mass rate of raw meal and coal at the precalciner and the feeding coal mass rate at the rotary kiln are selected as the main independent variable and control parameters, and the specific standard coal consumption is determined as the key performance parameter and the optimization objective function. The mean square error and the correlation coefficient of the established neural network model are 12.84 and 0.89, respectively. The relative errors of approximately all prediction data (92.52 %) are within ±5 %. The optimal values for the raw meal feeding rate, the coal feeding rate into precalciner, and the coal feeding rate into rotary kiln are 259.57 t/h, 7.84 t/h, and 7.40 t/h, respectively. In that optimal condition, the specific standard coal consumption reaches 80.00 kgstandard coal/tclinker (This is a relative value, as there is a slight drift in zero point of the factory's instruments). A highly accurate neural network model is developed, which can significantly reduce standard coal consumption and improve industrial energy efficiency.

Phase and microstructure evolutions of fiber reinforced aerogel composites with different fiber components during calcination

In the high temperature industry, controlling the external surface temperature of the kiln shell is crucial for reducing heat loss, energy consumption, and carbon emissions. While aerogels are esteemed for their superior thermal insulation properties and considered as optimal materials in the thermal insulation layer of energy saving lining for burning zone of cement rotary kiln, their structural integrity at elevated temperatures confines their applications to medium and low temperature settings. To overcome this limitation, the fiber-reinforced aerogel composites have been developed to bolster the high-temperature endurance of aerogel products. Notably, composites containing ZrO2-enhanced fibers exhibit significantly higher resistance to thermal degradation from local overheating, such as flame impingement, compared to their counterparts without ZrO2. However, the mechanisms of performance degradation and the reinforcing role of ZrO2 in fiber reinforced aerogel composites at high temperatures especially above 1000 °C, remain unclear. This study specifically focuses on the thermal conductive properties of commercial aerogel felts, both with and without the inclusion of ZrO2 across a range of temperatures, and examines the subsequent phase transitions and microstructural evolutions upon thermal treatment. Critical analyses of heat flow, mass change, density, linear shrinkage, and pore size distribution during the calcination process were conducted. After 6 h of heat treatment, composites with ZrO2-enhanced fibers retained an 81.44 % porosity, unlike composites without ZrO2 which sintered and became denser. The experimental findings demonstrate that the performance of fiber reinforced aerogel composites mainly depends on the fiber’s framework microstructure and fiber-aerogel reactions, which provides the references for developing excellent aerogel composites and evaluating of the usability in high temperature zone of kiln.

Continuous rotary kiln pyrolysis of cassava plant shoot system and wide speciation of oxygenated and nitrogen-containing compounds in bio-oil by HESI and APPI-Orbitrap MS

This work proposes the pyrolysis of the cassava plant shoot system biomass and a comprehensive chemical characterization of the resulting bio-oil. The highest yields of liquid products were obtained at 600 °C, with 12.6 % bio-oil (organic fraction), which presented the lowest total acid number of 65.7 mg KOH g−1. The bio-oil produced at 500 °C exhibited the highest total phenolic content of approximately 41 % GAE, confirmed by GC/MS analysis (33.8 % of the total area). FT-Orbitrap MS analysis found hundreds of oxygenated constituents in the bio-oils, belonging to the O2-7 classes, as well as nitrogen compounds from the Ny and OxNy classes. Higher pyrolysis temperatures resulted in more oxygenated phenolics (O4–7) undergoing secondary degradation and deoxygenation reactions, generating O2–3 compounds. Additional classes affected were O3–5N2–3, while O1–2N1 presented more stable compounds. These findings show that cassava bio-oils are promising sources of renewable chemicals.

Inhibiting the Accretion in the Coal-Fired Rotary Kiln of High-Silica Iron Ore Pellets Application by Reducing Fines Generation and Liquid Phase Formation

Inhibiting the Accretion in the Coal-Fired Rotary Kiln of High-Silica Iron Ore Pellets Application by Reducing Fines Generation and Liquid Phase Formation

Pyrolysis of shenmu coal to prepare blue-coke used as reductant

Blue-coke is a form of granular char prepared by medium-low temperature pyrolysis of low-rank coal. As a reductant, it has been widely used in calcium carbide production, ferroalloy, copper pyro refining, and ferrosilicon production in China due to the abundant reserves of raw coal and its excellent performance. However, there is little research on the pyrolysis process of granular coal to produce blue-coke and its characteristics as a reductant. Thus, the effects of pyrolysis temperature, heating rate, particle size and holding time at the final temperature on blue-coke preparation were investigated in a rotary kiln reactor. The quality index of blue-coke as a reductant and its properties, including the element composition, surface function groups, carbon forms, reactivity and lower heating value under different pyrolysis temperatures, were analyzed in detail. It is demonstrated that the pyrolysis temperature had a more significant impact on the quality of blue-coke compared to other pyrolysis conditions. With the rise of pyrolysis temperature, the blue-coke’s C/O and C/H increased. With the particle size and heating rate increased, the temperature gradients developed within the granular coal during the pyrolysis process led to the volatile release shifting to higher temperature zone and more secondary reaction occurrence. Nevertheless, the secondary reaction was restrained in the rotary kiln with good heat and mass transfer. The indexes of blue-cokes as reductants were met by the chars produced at temperatures from 550 oC to 750 oC with a holding time 60 min at this temperature and a heating rate of 10 oC/min. As the key index of blue-coke, the electrical resistivity decreased with the increase of pyrolysis temperature. It was found to be closely related to the removal of H and O heteroatom at the pyrolysis temperature below 700 °C. While at the higher temperature, the development of graphitized carbon structure took a major role on it. Nonetheless, the crystallite sizes of the blue-coke obtained under this low temperature pyrolysis were small and the carbon forms were turbostratic. These resulted in the blue-coke's high combustion reactivity, which would gradually decline with the rise of pyrolysis temperature.

THE VARIATIONS OF CLINKER SUPERPARAMAGNETIC VALUE FROM PT. SEMEN PADANG BY USING A BARTINGTON MAGNETIC SUSCEPTIBILITY METER SENSOR TYPE B

Clinker is an important material in the cement making process. Before clinker is formed, the raw material is burned in a Rotary Kiln at a temperature of up to 1450°C, then cooled in a Greet Cooler to a temperature of 100°C and produces clinker. This research is to determine variations in the superparamagnetic value of clinker based on the magnetic susceptibility value. The method is the rock magnetism method using theMS2B. Clinker samples are takenhourly every day from the Semen Padang Factory. The 휒푙푓value obtained varies between 3.2×10-8m3/kg to 22.6×10-8m3/kg. The superparamagnetic values obtained also varied, ranging from 0.0%-7.4%. Based on the 휒푓푑%obtained, there were 136 clinker samples containing less than 10% superparamagnetic grains, and 32 samples includedthe 휒푓푑%medium had a percentage of 2%-10% where the samples contained superparamagnetic grains. Between 10% and 75% is a mixture of fine and coarse superparamagnetic grains.

New method for measuring and analyzing the deformability and eccentricity of the ferrule kilns

In the industrial sector, particularly in the cement industry, the key aspect of the production process is the production of clinker through the use of a rotary kiln. Due to the large volume and high temperature involved, these complex structures are subjected to stress and deformation during operation. Therefore, it is crucial to conduct regular control measurements to verify the compliance of the basic geometric parameters. In this article, we examine the literature on various control techniques, with a particular focus on the misalignment of the rotating axis of the ferrule. This method was experimentally demonstrated by creating a prototype to validate it, and the results obtained by the prototype were then compared to those obtained by the coordinate measuring machine. The results indicate that the proposed method is effective for determining the real axis of the rotary kiln (eccentricity) and the ovality of the shell structure. With this purpose, the article proposes a new solution for processing spatial data using a mathematical method based on the geometric parameters of the shell structure. This study can be used to develop tools for controlling rotary kilns, particularly in the data collection process.

Incineration-source fingerprints and emission spectrums of dioxins with diagnostic application

Despite increasing waste-to-energy (WtE) capacities, there remain deficiencies in comprehension of 136 kinds of tetra- through octa-chlorinated dibenzo-p-dioxin and dibenzofurans (136 PCDD/Fs) originating from incineration sources. Samples from twenty typical WtE plants, encompassing coal-fired power plants (CPP), grate incinerators (GI), fluidized bed incinerators (FBI), and rotary kilns (RK), yielded extensive PCDD/F datasets. Research was conducted on fingerprint mapping, formation pathways, emission profiles, and diagnostic analysis of PCDD/Fs in WtE plants. Fingerprints revealed a prevalence of TCDF, followed by PeCDF, while CPP and RK respectively generated more PCDD and HxCDD. De novo synthesis was the predominant formation pathway except one plant, where CP-route dominated. DD/DF chlorination also facilitated PCDD/F formation, showing general trends of FBI > GI > CPP > RK. The PCDD/F emission intensities emitted in air pollution control system inlet (APCSI) and outlet (APCSO) followed the statistical sequence of RK > FBI > GI > CPP, with the average I-TEQ concentrations in APCSO reaching 0.18, 0.08, 0.11, and 0.04 ng I-TEQ·Nm−3. Emission spectrum were accordingly formed. Four clusters were segmented for diagnosis analysis, where PCDD/Fs in GI and FBI were similar, grouped as a single cluster. PCDD/Fs in CPP and RK demonstrated distinctive features in TCDD, HxCDD, and HxCDF. The WtE plants exceeding the limit value tended to generate and retain fewer TCDD and TCDF yet had higher fractions of HxCDD and HxCDF. The failure of APCS coupled with the intrinsic source strength of PCDD/Fs directly led to exceedance, highlighting safe operational practices. This study motivated source tracing and precise evaluation of 136 PCDD/Fs based on the revealed fingerprint profiles for WtE processes.

Experimental Studies of Fluidized Bed Calcination of Granulated Clay Material.

The work presents a detailed analysis of the possibilities of the thermal processing of clay raw material granulates in a fluidized bed reactor powered by coal fuel. Potential customers of calcined granulates include the following: plants producing refractory materials for the steel industry, producers of refractory concrete, sanitaryware plants, tile plants, large-size tile plants, industry abrasives, chemicals, paints, paper, food and medical industries and others. The advantage of the presented fluid bed calcination technology is the possibility of the continuous operation of the reactor and the short time of the material in the bed, compared to the previously used methods of calcination in a shaft and rotary kiln, which lasts less than twenty minutes in the temperature range of 650-850 °C. During the experimental studies of calcination in the fluidized bed layer, the influence of the type of coal, its particle size and the mass share of coal in the feed mixture on the calcination process and the final product obtained was analysed. As a result of the conducted research, it was proven that solid fuels such as anthracite and steam coal type 31.2 (flaming) can be successfully used in the fluidized bed calcination process of clay materials. The key parameter determining the fluidized bed calcination process is the fuel particle distribution.