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KELLER implements one of the most modern and flexible brickworks in the Russian Federation

With engineering, machines and plants, the four traditional brand names Morando, Rieter, Novoceric and KELLER ICS implemented in 2014 a complete production line for the manufacture of high-quality heavy clay products as per GOST 530-2012 and GOST 32311-2012. 42.3 million Russian NF units of very high quality facing bricks are now manufactured per year on an industrial area of 35,000 m2. Moreover, the fully automated production line is designed to manufacture a wide range of ceramic products now: Facing bricks in different sizes, colours and surface design, pavers in various sizes and unique products with a “flashing” effect, a characteristic feature of firing with reduced oxygen. For potential customers, the creative interplay between architecture and the art of brick firing generates a new space for structure and design in faced brickwork façades and paving bricks.On 10 July 2014, the holding company OOO “Sphera”  officially inaugurated its new brick works OOO "Dubensky Kirpitschny zawod" in the Russian Republic of Mordovia, 600 km southeast of Moscow. The bricks are sold under the name “STOLZ”. One of the most modern and flexible brickworks not only in the Republic of Mordovia, but in the entire Russian Federation was established on the old factory site.

Tailor-made filling plant for the clay deposit

A fully automated covered clay deposit was integrated into the brickworks to ensure an uninterrupted production even in the winter period. A front-end loader feeds the local clay raw material and clay from other sources separately  from the expertly piled up cone to a roofed exterior box feeder with non-stick inner coating. The feeding material is partially crushed by two mechanical moving shafts with special paddles. Furthermore, this equipment allows a homogeneous material feed to the outgoing belt conveyor. The roller crusher type WB 46-100-M ensures pre-crushing of the respective raw material. Materials that are not supposed to be crushed, such as rough stones, frozen material chunks or coarse contaminants, are singled out at this point. The clay deposit consists of a total of eight boxes with a surface area of approximately 2,600 m². It is fully automatically loaded with the material crushed in the pre-preparation area. A conveyor leads the material into the building and forwards it to an overhead central belt conveyor positioned below the ceiling of the building. This belt conveyor leads to the box to be filled and puts the material on one of the two reversible head belts which fill the box with an optimal material quantity. The entire innovative conveyor systems are of modular design.

Highly efficient clay preparation and shaping equipment

A front-end loader fills the raw materials into three box feeders from where outgoing belts forward them to the preparation area. Frequency converters are continuously adjusting the speed of the drives of the slat conveyors or rubber belts. Each box feeder is equipped with a balance for the accurate dosage of the raw materials and components; the material flow data is recorded over a defined area of the belt. A big bag dosing station equipped with a frequency converter also allows the introduction of additional barium carbonate or colour pigments to the factory blend if required. A conveyor system then forwards the weighed factory blend to the Rieter pan mill KAF 20/60. An upstream metal detector singles out metal parts in the raw material flow and discards them on a reversible sorting conveyor. The ground material then enters the pan mill through a central material feed. The material is further crushed on the inward roller track which has a closed bottom. Scrapers then lead it to the outward roller track equipped with a perforated bottom. The shearing and pressing forces squeeze the material through the perforations, and it falls on a counter-rotating collecting plate beneath the pan mill from where a belt conveyor moves it to the next grinding stage. A moisture control and regulating system controls the addition of water to the pan mill to such an extent that the material moisture remains homogeneous for the further preparation process.

The subsequent roller cascade works in three stages. The first mechanical preliminary roller mill crushes the factory blend with a grinding gap of approximately 2.0 – 2.2 mm. The second mechanical fine roller mill with a grinding gap of approximately 1.0 – 1.2 mm continues crushing the material before it then enters the subsequent hydraulic high-performance fine roller mill with a maximum grain size of 0.6 – 0.7. SYNCHRON-type material distributors positioned immediately in front of the roller mills spread the factory blend evenly on the flat inlet belt conveyor across the effectively usable roller width to avoid irregular abrasion of the rollers. All roller mills are equipped with  automatic turning tools that have special cutting devices for different hardness grades of the shell coating, thus providing means for turning the roller shells if required. The preparation units are connected to a piping system which leads to a central dedusting installation. A rotary valve is used to continuously reintegrate the collected filtered dust into the material stream on the belt conveyor downstream of the pan mill, therefore disposing of the dust in a sustainable way. The automatic belt conveyor system feeds the semi-plastic prepared factory blend either to the longitudinal clay storage or alternatively directly to the buffer box feeder at the beginning of the shaping line. In the longitudinal clay storage the factory blend is temporarily stored and undergoes a ceramic aging process that leads to a better plasticity and more homogeneous moisture of the blend during the shaping process. A computer-controlled belt conveyor system feeds the material into the clay storage boxes to obtain a profound mixture of the incoming material. An automatic, also computer-controlled longitudinalexcavator removes the aged factory blend  from the longitudinal clay storage and forwards it to the shaping line. The starting point of the shaping line is a box feeder that acts as a buffer between preparation and shaping. Downstream of the shaping group is another metal detector to sort out any leftover metal parts from the material, thus preventing unnecessary wear of the subsequent machines. The circular screen feeder SRB 1900 combines dosing, mixing and homogenising functions.This machine is particularly ideal in  the shaping plant to guarantee a homogeneous material and throughput for the following machines. If necessary, water is added to the material mix in the circular screen feeder. The material is then again thoroughly homogenised and reaches appropriate moisture for further treatment. It is then pressed through the screens and forwarded to the extruder. An automatic moisture control system measures and controls the pressure at the pressure head and also the current consumption of the double shaft mixer and the worm extruder. The material is again thoroughly mixed in the double shaft mixer with compaction zone, afterwards it is aerated in the following vacuum chamber and fed into the worm extruder. When the clay strands coming from the double shaft mixer enter the vacuum chamber, rotating knives and toothed combs shred them into small pieces, thus allowing a fast and efficient aeration. The material is compacted in the cylinder of the worm extruder and then forwarded to the pressure head and the die. Depending on the size andshape of the future  product, the extruder comes with three different pressure head models with a brake system that can be regulated from the outside. The dies were specially adapted to the rheological characteristics of the factory blends and provide very smooth brick surfaces and low dimensional tolerances of the finished products. Cutting waste may arise at the start of the production or during a product size change. For this purpose, an automated belt conveyor system is available near the cutter line which continuously removes any waste material from the production hall. A column-mounted slewing crane is installed near the vacuum unit type Variat SP 560/500 to facilitate the work of the operators when changing dies or wearing parts.

An extremely compact machine installation for the production of a wide range of bricks

High-precision production of green bricks

The production line offers the option to provide the clay column leaving the extruder with different surface structures or a sand coating. The texture roller optionally available for this purpose is a rail-bound system integrated into the plant with plug-in connectors for easy and flexible use. On the cutting line, different products can be cut to the required cutting length (height of the brick) from an endless clay column coming from the extruder. In the production line, the universal cutter with its very precise vertical cutting system cuts facing bricks, pavers and porous hollow bricks with dimensional accuracy up to a clay column width of 500 mm. The movements of the cutting table and the cutting wires are controlled with the “electronic cam disc”, i.e. a combination of servo motor, crank drive and specially developed control system. This permits downloading the ideal curve for any cutting length from the control system. The drives follow a product-dependent profile where the profiles consist of interpolation points that are stored in a data block in the PLC. During a product change the Profibus system assigns the corresponding profiles to the specific drives. The universal cutter is equipped with an automatic wire feeding device that provides a very high availability of the machine. An error message is displayed during a possible wire breakage, the extruder is blocked and the shaping and cutting lines are stopped.

The various types of facing bricks and pavers can optionally be produced with chamfer on all four sides provided by the integrated chamfering system “Stargate”. A turning device turns porous bricks by 90° to the direction of movement to permit better handling and ideal drying.

Automated product and pallet transport

When the products are collected on the grouping conveyor, a transfer device moves them to the provided pallets (laths). A horizontal chain conveyor moves the loaded pallets to a vertical conveyor that collects a pile of loaded pallets in 14 layers one on top of the other. The gathering frame temporarily stores five rows one behind each other and holds them ready for the finger car. This electric rail-bound finger car then forwards the extruded products into the drying installation. A transfer car moves the finger car laterally in front of the drying chambers. This transfer car is also an electrically driven rail-bound machine. A driver sitting on the finger car operates these vehicles. After the drying process, now in reverse order, the finger car removes the pallets with the dried products from the chamber and forwards them to the gathering frame on the dry side. A toothed belt conveyor takes the pallets loaded with dried products from the vertical conveyor. A lifting device then lifts the products up to the height necessary to be taken over by the transfer gripper. The doublerow transfer device transfers the products to the belt conveyor for further transport to the setting installation. When producing blocks, only every second layer in the drying chamber will be occupied. In this case, pallets that are not used are automatically collected and stored by a pallet storage machine. The entire innovative machine installation is of state-of-the-art modular design.

Proven chamber dryer plant design

The dryer plant was designed as a chamber dryer to ensure a high quality standard and to provide a wide product range. The dryer consists of 21 separately operating units (double chambers) which permit an extremely flexible production of the different brick types and sizes. The individual double chambers of the chamber dryer installation are controlled separately, thus guaranteeing that each brick type and each size can be dried individually with its own ideal drying program. Therefore, product size changes and production fluctuations do not have negative effects on the drying quality. The time-dependent temperature and humidity curves (climate control) can be separately assigned to each double chamber and are optimally adapted to the respective contents of the chamber.

Another advantage of separately operating double chambers is that drying and production errors are immediately identified and can hence be eliminated very quickly. Therefore, a chamber dryer substantially lowers the drying risks with regard to output deficiencies or inferior quality, especially when the raw material used is difficult to handle. The finger car brings the pallets into the chambers and sets them on the supporting ledges. When the chambers are full, they are semi-automatically closed with hinged doors and the drying process starts. The drying principle is horizontal circulation drying, i.e. the air within the individual units is circulated again and again until it has reached the largest possible degree of saturation in relation to the drying curve. Only then the air is led through the wet air collecting duct and is exhausted through the wet air stack to the outside air.

Due to its design and equipment with appropriate measuring instruments the chamber dryer is ideal for exact monitoring and control of the drying climate. A fan presses the hot air needed for drying into the main conduit located above the drying chambers. This conduit is provided with air regulation valves that take over the distribution of air into the individual drying chambers. The saturated air is then discharged through conduits connected to a wet air stack. The wet air outlet lies approximately 10 m above ground level. Axial fans are installed in the wet air stack and lead the wet air to the outside. The process computer uses the individual drying program that is available for each product to control the addition of hot air or the discharge of wet air. For optimal energy efficiency, the recovered waste heat of the tunnel kiln is primarily used to heat the dryer. Every operating unit of the drying installations is equipped with two air circulation units with four axial fans that circulate the air within the drying chambers through the racks holding the products to be dried. The drying chambers are heated both with recovered waste heat from the tunnel kiln and with natural gas burners. The burners are designed to operate  in two stages. The temperature in the drying chambers is 100 °C max. The individual chambers are equipped with temperature sensors to monitor and record the temperature.

The whole dryer installation is automatically controlled by a process computer system. During loading of the chambers and subsequent unloading after drying the air regulation valves are closed and the fans are switched off. Hot air can therefore not enter these chambers. The chambers are unloaded by a finger car and a transfer car.

High flexibility and user-friendly operation of the fully automatic setting installation with high-speed industrial robots

Equipment and stations tailored to the specific needs of the customer around the conveying systems leading to the setting installation make sure that at the end of the passage the dried products, depending on their size and type, are set down and stacked on the tunnel kiln car according to a predefined pattern. The dried products leave the chamber dryer with a certain temperature and enter the setting installation where they are arranged, turned, doubled, aligned, grouped, and positioned to be picked up by the special gripper of the high-speed industrial robot. Immediately after having set the dried products on the double row conveyor 1 the products run against a stopper and are aligned perpendicularly to the travelling direction. The double row conveyor 2 only works when the diffuse reflective sensor is engaged to close the gaps between the product groups. From the transfer device with counting unit the double row conveyor 2 only takes up the number of dried products required to form a row. The first belt conveyor with subsequent roller conveyor moves the individual rows with their exact positions through the various handling devices and transfers the newly arranged product rows to the second belt conveyor. The individual stations are:

  • The first adjusting device on both sides serves for a symmetrical adjustment of the product rows towards the centre of the conveyor belt.
  • A turning device rotates the product rows by 90° or 180°. 
  • The second adjusting device on both sides serves for a symmetrical adjustment of the manipulated product rows towards the centre of the conveyor belt.
  • The row grouping device groups the products at defined different spaces. The grouping process is a program-controlled operation where the individual products are lifted and set down. The grouped products leave on a roller conveyor.

The created product layers are positioned on the belt conveyer where they are waiting to be picked up. The special gripper of the high-speed industrial robot takes up the respective product layers, lifts them up from the belt table and sets them down on the tunnel kiln car following the pre-defined setting pattern. A special feature is the ability to stack the two visible sides of the products one on top of the other (face-to-face). The entire innovative machine installation is of state-of-the-art modular design.

A kiln concept based on energy optimisation

On the process engineering side, the tunnel kiln was developed on the basis of the different raw material mixes necessary for the production of the customer's heavy clay product range and in co-operation with the specialised departments who put their main focus on energy efficiency. Thanks to a precise control and regulation system, the tailor-made firing technology ensures a very low specific primary energy consumption and maximum economic efficiency. The same applies to the power consumption of the tunnel kiln. Our optimised concept works with fan technology using the lowest efficiency rating and highest energy efficiency, thus requiring very low electric energy input.

Upstream of the firing process in the tunnel kiln itself, the heavy clay products pass an insulated holding room and preheater. Both are fed with waste air from the tunnel kiln. The holding room immediately follows the fully-automatic setting installation and is located on the outside kiln car track system on a track in parallel to the tunnel kiln. This arrangement prevents reabsorption of humidity in the dried products and averts deterioration in quality of the final products. The preheater, equipped with process engineering material, is designed as a closed inlet and outlet sluice and maintains a constant pressure and draught profile within the tunnel kiln. This profile is used to control flue gas and air flow during the kiln operation process. Furthermore, the tunnel kiln is equipped with four lateral flue gas circulation units in the heating zone. The tunnel kiln is mainly heated from the top. A burner group, consisting of a certain number of injector burners, uses a stoichiometric mixture of natural gas and air as fuel to fire the tunnel kiln through the feed holes. Two burners each across two feed hole rows constitute a burner group in the firing zone. The top burner plant consists of an injector burner system developed by KELLER ICS and provides a very homogeneous temperature distribution across the entire firing channel cross section. The last two burner groups are equipped for “flashing”. For this purpose, the natural gas conducting components  were designed to resist a higher gas pressure to be able to create a large range of products with varying play of colour. All burner groups are equipped with a valve train at their fuel entrance point that causes a shutdown of the burner group during the pushing process or in case of potential malfunctions. The generated hot flue gases flow opposite to the direction of motion of the products to be fired from the main firing zone through the tunnel kiln car setting or through the lateral gaps and ceiling gaps towards the entrance of the kiln. Flue gas circulation in the heating zone of the tunnel kiln car positions of the heating-up zone provide additional circulation of the flue gases and a more effective temperature exchange with the products to be fired. The flue gases are cooled down to above the dew point and a flue gas fan extracts them in the ceiling and walls area of the kiln entrance and emits them through a stack to the atmosphere. A steel shell serves as an inner lining and makes the tunnel kiln gas-tight.

At the end of the tunnel kiln a contravec fan presses ambient air into the tunnel and on the fired bricks to cool them down. A rapid cooling system that injects ambient air is installed at the end of the tunnel kiln to cool the bricks down more rapidly. At the same time it serves to adjust the cooling curve. The major part of the air heated in this process is extracted through the upper and lower hot air extraction system and is then fed into the hot air collecting pipe that leads to the dryer to heat it up in return. This extraction system works in relation to the pushing capacity of the kiln cars and is temperature-controlled through servo drive actuated valves in the extraction pipes. The cooling air remaining in the kiln atmosphere flows through the firing zones and contributes to the oxidation of colouring substances and material to be burnt out of ceramic bodies.

The entire kiln plant is equipped with automatic measuring and controlling installations. A process computer system is used for process control, monitoring and optimisation. Safetyrelevant functions are monitored by appropriate switching facilities, such as flue gas draught monitoring, pressure gauges and ring balances. A safety circuit ensures that it is only possible to activate the gas supply or the burner plant when certain conditions are given. All error messages are accompanied by an audible alert and can be listed and recorded on the computer. Production parameters for the corporate quality management can be stored in the integrated database.

Compact and user-friendly fully automatic unloading and immersion installation with high-speed industrial robots

A 4-axis high-speed robot picks up the fired heavy clay products from the tunnel kiln cars that are now standing in the unloading position and transfers the products to a wide belt conveyor. Similar to the setting installation, the fully automatic unloading installation is equipped with tailor-made handling devices/stations in accordance with the specific needs of  the customer on the line leading to the packing station where different fired bricks are suitably arranged for palletizing. The double-row transfer gripper lifts the positioned brick row up from the deposit position on the belt conveyor and places the single row on the double-row sorting chain conveyor. While the sorting chain conveyors move the end products to the transfer point to the robot equipped with a double-row row gripper, the operator can sort out and discard any faulty products either by checking them visually or by knocking on them to hear if they sound right. In one operating cycle the 4-axis high-speed industrial robot takes up a square dispatch pack layer and places it on the lifting plate of an immersion tank. Depending on the products, three immersion tanks in total can be loaded at regular intervals. After loading, the lifting plates are lowered into the immersion tanks and remain completely immersed below the water level in their bottom holding position. When they emerge again, the robot picks up the brick rows with stack grippers and suction devices in the gripper. In a first cycle, the 4-axis high-speed industrial robot picks up an empty wooden pallet (1000 x 1000 mm) from the feeding chain conveyer and places it on the chain conveyor of the packing line ready to be stacked. In a second cycle, the robot alternately picks up a layer from the lifting plate and a ready-cut paper sheet and stacks the fired bricks layer after layer on the positioned pallets until a pack is full.

The ready dispatch pallets are then forwarded through the packing line on several connected chain conveyors to arrive at a stretch hood machine that will provide a high packing integrity and flexibility for the dispatch pallet. Packaging with stretch hood technology gives distinctly more stability for further handling and transport of the dispatch pack. Outside the production hall fork-lift trucks pick up the dispatch packs from the chain conveyor and move them to the storage place for finished goods. The entire innovative machine installation is of state-of-the-art modular design. This modular concept offers ideal operability and high flexibility for the operating company and for the operators themselves.