Activated carbon is black powder or block, granular, honeycomb amorphous carbon, there is also orderly arrangement of crystal carbon. Because it contains 80%-90% carbon, it is often used as a hydrophobic adsorbent. The main preparation principle is to convert all carbon-rich organic materials (such as coal and wood) into activated carbon through pyrolysis at high temperatures and certain pressure. In the whole production process, the activated carbon rotary kiln is a very key piece of equipment in the high-temperature carbonization stage.
The material produced by activated carbon rotary kiln has the advantages of strong chemical reaction ability, small volume density, large specific surface area, etc., and activated carbon is one of the main auxiliary materials in the steel making, coking, calcium carbide and other industries at home and abroad.
The activated carbon rotary kiln has many advantages such as simple operation, low carbon, and environmental protection, and is one of the commonly used equipments for processing activated carbon. It has a reasonable structure, well-produced, high output, low energy consumption, convenient operation.
The activated carbon rotary kiln includes a rotary cylinder, kiln head, kiln tail, sealing and supporting devices, etc. In order to ensure that the kiln body rotates slowly when the power supply is interrupted, auxiliary devices are specially set up in the driving part. In addition, the kiln head is sealed with shell and cover type, which ensures the sealing performance of the activated carbon calcining process and has the characteristics of environmental protection, energy-saving, and automation.
When activated carbon is calcined in the rotary kiln, the temperature is between 950 and 1050. The temperature can be adjusted according to the amount of activated carbon material to finally meet the customers requirements for finished products. This technology has stable performance and is the preferred equipment in the environmental protection renewable resources industry.
Active carbon rotary kiln has been developed and produced so far with various models. According to different decomposition forms, it can be divided into two types: external calcining kiln and preheating calcining kiln. Its output is 100-10000t/d.
The working process of the activated carbon rotary kiln is that the qualified activated carbon after treatment is stored in the silo, which is lifted by the elevator and transported into the top silo of the preheater. At the top of the preheater, the feeding amount is controlled by the upper and lower two material level meters, and then the activated carbon is evenly distributed to each room of the preheater through the blanking pipe.
Activated carbon is heated to about 900C by 1150C kiln flue gas in the preheater, about 30% decomposition, pushed into the lime rotary kiln by hydraulic push rod, activated carbon is sintered and decomposed into CaO and CO2 in the rotary kiln. The decomposed activated carbon enters the cooler, it is cooled to 100C by cold air and then discharged. The heat exchanged 600C hot air enters the kiln and is mixed with gas for combustion. The waste gas enters into the bag filter through the induced draft fan and then into the chimney through the exhaust fan. If the user has other requirements, it can be completed by other auxiliary equipment.
Activated carbon prepared by high temperature has been widely used in petrochemical, electric power, chemical industry, food, gold, environmental protection, and other industries. It is mainly used for water purification and sewage treatment with its hydrophobic adsorption property. The application of activated carbon also includes decolorization and purification of beverages and wine in the food industry, gold extraction, harmful gas, waste gas treatment, purification, etc.
In recent years, with the continuous development of the economy and the gradual improvement of peoples living standards, people have put forward higher requirements for the living environment such as the safety and purity of food, medicine and drinking water, and the market demand of activated carbon is constantly expanding. With the development of society and the improvement of peoples environmental requirements, activated carbon will play a very important role in the environmental protection industry, and the investment in the activated carbon market has a considerable prospect.
OurCustom Rotary Kilns are based around process first and foremost. Designed to ensure correct residence time at hold temperature of 20 minutes -not 10 minutes, they ensure stable progressive feed of your carbon with reliable three zone heating with independent controls, robust thermal lifter designs, co-current movement of reaction products and correct thermal conduction area and bed thickness defining retort size.
Comprises an agitated conical bottom vessel with transfer eductor, fresh carbon feed chute and electric monorail for supply of the carbon to your elution system. Gentle agitation reduces the carbon fines introduced into your CIL/CIP system
Used in conjunction with the Transfer Water System, this system recovers carbon fines with high gold bearing loads from the transfer water assisting to reduce the high (up to 50g/t loss) carbon losses experienced in the CIL plant.
This system recovers hydraulic transfer used for carbon movement around the circuit. Hydraulic transfer rather than impeller pumps reduces attrition of the carbon extending your carbon life and lowering solids to tails. The transfer water recovery system incorporates a large transfer water vessel with a transfer water pump system providing water for carbon transfer around the plant.
This sludge recovery equipment aides in the recovery of gold sludges when stainless steel mesh cathode wire is used in the electrowinning cells rather than the traditional mild steel wool where gold is plated to the wool. Sludges and gold fines are collected and dried to a cake suitable for post thermal drying prior to being smelted in the barring furnace.
QSY Rotary Kiln is mainly used for activated carbon regeneration in Gold CIP Production Line. After gold loaded carbon desorption, it is washed by dilute sulphuric acid or nitric acid to remove the accumulation such as calcium carbonate, after several working cycle, the carbon must be thermodynamic activation to regain the activity. The thermodynamic activation is done in the QSY rotary kiln. To heat the carbon in 700 under the conditions of air isolation,holding 30 minutes, and cooled in the quench tank, screening by the 16 mesh screen to remove the fine carbon, the regeneration active carbon return to the carbon adsorption circuit. This process is the core part of adsorbs gold from cyaniding pulp by active carbon: including 7 steps, leaching pulp preparation, cyaniding leaching, carbon adsorption, gold loaded carbon desorption, pregnant solution electrodeposit, carbon regeneration, leaching pulp.It is very useful gold recovery method in mineral processing.
QSY rotary kiln features automatic constant temperature control, high efficiency and energy conservation etc. and is designed for regeneration of active carbon after dehydration for gold mine and the roasting , volatilization, liquate and calcination of raw material in the industry of metallurgy, chemical industry, environmental protection.
Nutec Bickley rotary kilns for carbon reactivation offer a very efficient way to clean activated carbon so that it can be reused. The kiln is based on the successful GFC design already used throughout the gold mining industry.
Nutec Bickley rotary kilns for carbon regeneration are furnished with a complete control system which will permit kiln operators to regulate all of the kiln parameters, such as carbon feed rate, process temperatures, steam flows, kiln pressure etc.
Both the entry and the exit of the drum are supplied with a spring-loaded rotary seal with a graphite impregnated seal medium and with an improved labyrinth system to stop the superelastic carbon from bouncing into the seal face and causing grinding and premature failure of the seal.
In our carbon regeneration kilns we have the ability to run at higher temperatures so that organic contamination is removed more efficiently. Regenerated carbon is very close to virgin carbon activation levels after treatment.
With our SCADA systems, the kiln operators are able to have complete control of their firing process, enhancing efficiency and productivity. Our latest Industry 4.0 developments integrate the latest technology to not only monitor the process, but also to keep the kiln operating in its peak performance with smart maintenance technology. All the data generated during the firing process is stored in our SCADA system, which then is used to generate reports, graphs and intelligence data, to help customers in their decision making process.
Our kiln system cools down the carbon with a quench tube, reducing the carbon temperature down to 250C (480F), in order to avoid thermal shock as the carbon is dropped into a quench tank for final cooling.
The steam is in turn superheated and it flows into the drum exit end to provide a very efficient supply of the process steam which both aids the regeneration and keeps the pressure controlled, to inhibit oxygen ingress. The steam flow can be adjusted.
Nutec Bickley rotary kilns for carbon reactivation are furnished with a complete control system which will permit kiln operators to regulate all of the kiln parameters, such as carbon feed rate, process temperatures, steam flows, kiln pressure etc.
The electric heating rotary kiln, also known as electric rotary kiln, is rotary kiln equipment that uses resistance material as an electric heating element for heating. Electric heating is generally used in indirect heating rotary kilns. The electric rotary kiln is important equipment for roasting metal oxides or chemical products in the non-ferrous metallurgy and chemical industries.
The heating elements of the electric rotary kiln use nickel-chromium alloy (1Cr18Ni9Ti or Cr25Ni20Si2) or iron-chromium aluminum alloy (0Cr13A14 or 0Cr25A15) to make spiral heating elements, which are generally installed on both sides and bottom of the electric heating rotary kiln. There are four groups of heating elements in the electric heating rotary kiln, that is, four heating temperature control zones, and the temperature of each zone can be set separately. Its rated heating power can reach 300 kW, which can meet the heating requirements of electric heating rotary kiln, and the power will be reduced after the stable operation of the equipment. The advantages of the electric rotary kiln heating device are that the kiln pipe is heated on three sides, the heating is uniform and the thermal efficiency is high.
Another type of electric heating rotary kiln heating furnace uses silicon carbide (SiC) as the heating element. There are two rows of silicon carbide rods, 24 in each row. A total of 48 silicon carbide rods are electrified to generate heat to heat the kiln pipe, and the heat is transferred to the material through the pipe wall. The temperature of the electric heating rotary kiln is controlled in three stages, and the temperature inside the furnace body structure is measured and controlled by three thermocouples. By increasing or decreasing the number of 48 silicon carbide rods energized, the temperature required for the oxidation and roasting of the material can be adjusted and controlled to realize automatic temperature control.
As the heating element, the silicon carbide rod is only arranged at the bottom of the electric heating rotary kiln. Although this arrangement is single-sided radiation heat transfer, because the kiln pipe rotates at a uniform speed, the heating of the electric rotary kiln is still very uniform. As the heating element of the electric heating rotary kiln, silicon carbide rods are easy to repair and replace without affecting the thermal efficiency of the rotary kiln and normal working conditions.
The complete system of electric heating rotary kiln consists of feeding device, kiln body, discharging device, electric heating device, control unit, etc. The electric heating device heats the surrounding environment of the materials in the kiln to gradually increase the temperature. When the temperature measured by the thermocouple reaches the requirement, the temperature will not continue to rise, and the material can be discharged after the reaction time reaches the specified value, and the whole process is safe and efficient.
Compared with gas-fired rotary kiln and oil-fired rotary kiln, electric power used by electric rotary kilns is the cleanest energy source. Electric energy can be easily connected to the factory and supplied to the electric heating rotary kiln along with the power supply line.
Pertaining to environmental protection, reactivation of spent Activated Carbon and its further re-use is an interesting opportunity. Activated Carbon is an environmental-friendly and recyclable product, which we reactivate at our two thermal reactivation sites in Germany and Austria whenever possible, offering our customers an attractive reuse option. For this purpose, we own three rotary kilns which are used to batch-wise reactivation of spent granular or extruded Activated Carbon from diverse application sources which may then be re-used. Normally, the original adsorption capacity of the carbons can be almost fully restored, hence the process is a sustainable environment-friendly and cost-saving alternative to disposal and/or fresh carbon. During the process of thermal reactivation, spent Activated Carbon passes through several stages of temperature in a rotary kiln, reaching more than 1000 C in the last zone. After desorption and pollutant pyrolysis, the now again un-loaded Activated Carbon is re-activated by steam. The pollutants released by the reactivation process are destroyed at high temperatures of up to 1200 C in a downstream incinerator stage followed by flue gas cleanup. Optimum process control tuned to the specific requirements and the different Activated Carbon grades ensures the production of a high-quality reactivate. The performance of the reactivation process is monitored by ongoing quality control of the reactivated product. At our Landeck site in Austria or in cooperation with certified partners, we can also offer incineration of spent carbon material which cannot be reactivated. Such material is e.g. used in the production process of calcium carbide. This closes the circuit and contributes to environmental protection. As we always focus on quality and environmental care, our reactivation facilities are licensed under the German Air Pollution Control Act [BimSchG] and operated in strict compliance with the permit requirements. For clients interested in reactivation, we offer three different ways of taking advantage of this service:
In order to produce cheap activation carbon for dioxin adsorption in waste incinerator, waste plywood, pinewood, and coconut shell were used as raw materials to produce activated carbon via steam gasification on a lab-scaled rotary reactor. The influence of temperature, steam flow rate, and activation time on activated carbon yield and properties was investigated. Experimental results show that at 800 years, with 30-min activation time and steam/char ratio equal to 2, the yield of plywood activated carbon reached 60.5%, which was much higher than pinewood. The iodine adsorption value was 943 mg/g, which is close to pinewood. The pore structure analysis results show that the activated carbon derived from pinewood and plywood is similar. The pores with diameter of 25 nm were well developed, which was suitable for dioxin adsorption in waste incinerator. In the end, the computational fluid dynamics (CFD) and discrete element method (DEM) were used for modeling and optimization of the rotary furnace. Calculation results show that internal friction between the particles or the degree of anisotropy of the particles will cause the particles in the furnace to form a larger accumulation inclination, which benefits the mixing of the material in furnace. The results show that both the Eulerian-Eulerian two-fluid method and the DEM can simulate the movement of particles in the rotary furnace.
Fateh T, Rogaume T, Luche J, Richard F, Jabouille F (2014) Characterization of the thermal decomposition of two kinds of plywood with a cone calorimeter FTIR apparatus. J Anal Appl Pyrolysis 107:87100
Hlosta J, Jezersk L, Rozbroj J, urovec D, Zegzulka J (2020) DEM Investigation of the influence of particulate properties and operating conditions on the mixing process in rotary drums: Part 2Process Validation and Experimental Study. Processes 8(2):184
Li W, Yang K, Peng J, Zhang L, Guo S, Xia H (2008) Effects of carbonization temperatures on characteristics of porosity in coconut shell chars and activated carbons derived from carbonized coconut shell chars. Ind Crop Prod 28(2):190198
Bell JG, Zhao X, Uygur Y, Thomas KM (2011) Adsorption of chloroaromatic models for dioxins on porous carbons: the influence of adsorbate structure and surface functional groups on surface interactions and adsorption kinetics. J Phys Chem C 115(6):27762789
Liu Y, Su F-Y, Wen Z, Li Z, Yong H-Q, Feng X-H (2014) CFD Modeling of flow, temperature, and concentration fields in a pilot-scale rotary hearth furnace. Metall Mater Trans B Process Metall Mater Process Sci 45(1):251261
Zhao, S., Chen, L. Utilization of biomass waste for activated carbon production by steam gasification in a rotary reactor: experimental and theoretical approach. Biomass Conv. Bioref. (2020). https://doi.org/10.1007/s13399-020-00921-9
The experimental and numerical results on production of activated carbon by waste.The surface area has been evaluated varying hold times in steam activation.The theoretical model shows results in good agreement with the experimental data.The energy balance was carried out about the experimental tests on pilot plant.
This work is focused on the production of activated carbon from waste tires by means of a two-steps process: steam gasification of starting material followed by steam activation of char. In particular the evaluation of the most appropriate hold time value for the activation step, in terms of quality and amount of activated carbons produced, and the energy balance of the overall process were performed. The hold time was choose as the best compromise between a high surface area of final product and a not excessively low burn-off value. Investigations were carried out through seven experimental tests on a pilot plant based on a rotary kiln reactor. Studies performed pointed out that, when other process parameters were kept constant (in steam gasification: temperature is 850C, steam to feed ratio is 1, mean residence time of material is 6min, carrier flowrate of N2 is 0.9Nm3h1; in steam activation: temperature is 920C, steam to char ratio is 2, carrier flowrate of N2 is 1Nm3h1), a hold time in activation step set to 3h is the best choice, resulting in a surface area of 786m2g1 and a burn-off value equal to 78.4%. Moreover, the energy balance of the overall process which goes from waste tires to activated carbon was performed: if 1kgh1 of waste tires are gasified and activated for three hours, an input power of 3.5kW is requested. After the experimental tests, a theoretical model was developed, based on the Arrhenius equation whose parameters were determined from a sigmoidal regression of the experimental data. The theoretical model showed results in good agreement with the experimental data, especially for hold times greater than 2h, and can represent a useful tool to make decision choices.