Raw Material and Production Process of Lightweight Expanded Clay Aggregate (LECA)

Lightweight expanded clay aggregate (LECA) or expanded clay (exclay) is a lightweight aggregate made by heating clay to around 1,200 °C (2,190 °F) in a rotary kiln. The yielding gases expand the clay by thousands of small bubbles forming during heating producing a honeycomb structure. LECA has an approximately round or potato shape due to circular movement in the kiln and is available in different sizes and densities. LECA is used to make lightweight concrete products and other uses. 

LECA is usually produced in different sizes and densities from 0.1 millimetres (0.004 in) up to 25 millimetres (1.0 in),commonly 0-4 mm, 4-10 mm, 10-25 mm and densities of 250, 280, 330, and 510 kg/m3. LECA boulder is the biggest size of LECA with 100–500 mm size and 500 kg/m3 density.       

Application of Lightweight Expanded Clay Aggregate:  

Common uses are in concrete blocks, concrete slabs, geotechnical fillings, lightweight concrete, water treatment, hydroponics, aquaponics and hydroculture. 

Clay Expanded Aggregate Plant:

The raw material of clay expanded aggregate is clay with suitable component, addition other materials if the component is not suitable, then granulate by process, and calcination in rotary kiln to become light expanded aggregate.

The clay expanded aggregate has features such as light volume- weight, high intensity, heat preservation, thermal insulation and so on, also high anti-seismic and compression resistance, non- poisonous, non-radioactive, environmental protection and energy saving, construction adaptability. 

Production Process:

The clay was storage in material shell. The storage capacity is around 30 days usually. The particle size of clay around 100-200mm, and send to material hopper by forklift, and fed   into roller crusher by the apron feeder under the hopper, the crushed clay conveyed into double shaft mixer by belt convey-  or for compulsive mix and stir, make the material size smaller and homogeneous, and come into double roller granulator for extruding granulate.

The pellet from granulator going into shaping screen though belt conveyor, after the shaping screen, the smaller pellet are screening out, and qualified pellet are send to plug-in type rotary kiln for preheat and calcination. The calcined pellet drop into cooler for cooling, and going into rotary screen for divided different size product for storage, packing and delivery. The cooling air in cooler is heated to high temperature secondary air which as combustion air comes into rotary kiln, it can be save energy like this. Fuel is send into rotary kiln by high pressure induced draft fan for combustion through multichannel burner, the high temperature exhaust gas with dust come into air cooler, after the  temperature of dust air cooling, then come into bag filter and escape into the atmosphere after purification in bag filter.

Sludge Expanded Aggregate Plant:

The handle methods for sludge have sea filling, embed, incineration and land utilize, but with many problems. If the handle sludge from sewage treatment plant by embeds, it costs a lot of processing costs and causes secondary pollution to the environment. Use sludge produce expanded aggregate, not only instead clay to produce expanded aggregate, save land, make waste profitable, but also high temperature sterilization, Curing heavy metal, to avoid pollution.

Production Process:

The sludge and clay are transported into plant by truck, storage in materials shell for natural drying sometimes, and then send to each hopper by forklift. One apron feeder under the clay hopper, and send clay to double roller crusher. It can be set several crusher to make clay size smaller, and then sent to double shaft mixer. Sludge also come into double shaft mixer by screw conveyor under the sludge hopper. Clay and sludge mixture in double shaft mixer fully, and sent to ageing yard for storage.

The ageing material are sent to hopper by forklift, and then through another double shaft mixer mixture, and go to double roller granulator for make pellet. The pellet come into shaper by belt conveyor, after shaper, the small pellet are screening out, qualified pellet are sent to plug-in type rotary kiln for preheat and calcinations. The calcined pellet drop to vertical cooler for cooling, and screening to different size products by rotary screen, storage in yard at final for packing and delivery. The cooling air in vertical cooler is heated to high temperature secondary air which as combustion air comes into rotary kiln; it can be save energy like this. Fuel is send into rotary kiln by high pressure induced draft fan for combustion through multichannel burner, the high temperature exhaust gas with dust come into air cooler, after   the temperature of dust air cooling, then come into bag filter and escape into the atmosphere after purification in bag filter.

Fly Ash & Sludge Expanded Aggregate Plant

Fly ash is the waste of the firepower power plant, and the sludge is the waste of urban water treatment plant, can also be the sludge in the bottom of River Lake. After mixture and aging of fly ash, sludge and clay, it can be made into construction aggregate through pelleting and calcination. In this way, the solid waste can be effective used. The clay used as adhesive which turn "waste" into wealth. Meanwhile, the high temperature sterilization can solidify the heavy metal and avoid pollution.

Production Process

The fly ash sludge expanded aggregate are made from fly ash, sludge and clay. The fly ash stores in the silo and discharge from rotary discharger in bottom of silo, then enter into double-shaft mixer through the belt weigher. The sludge stores under the rain proof shed, after a period storage with moisture evaporation, will be sent to sludge silo by forklift and entered into double-shaft mixer through the belt weigher. The clay will be feed into roller- type crusher by apron conveyor, and enter into double-shaft mixer as well.

The fly ash, sludge and clay is sufficiently mixed in the mixer, and then conveyed to aging storage yard. Through 15-20 days aging period, it will be sent to double shaft mixer again for break- up and mixture, then feed into double roller granulator. The pellet made by granulator will be conveyed to shaping screening machine by belt conveyor. After rounding off, the small size will be screened out, while the qualified pellet will be feed into plug- in type rotary kiln for preheating and calcination. The pellet after calcination will be sent to vertical cooler for cooling, then enter into rotary screener to get different size finished products, and store in each storage yard. The high temperature secondary air produced by the vertical cooler enters into rotary kiln for assistant burning to save fuel. Through multi-channel burner, the fuel is sent to rotary kiln for combustion by high pressure fan. After cooling temperature in air cooler, the high temperature exhaust gas in kiln tail will enter bag filter for dust removal and exhaust.

The above are the basic introduction of expended aggregate production process by different materials. ZK Corp had been involved in the ceramsite industry since 2005, which had opened up a new process method for the construction of new environmentally-friendly and energy-saving expended aggregate and ceramsite proppant. ZK Corp has the capability of complete service for designing, equipment manufacturing, installation and commissioning, training, and guaranteed operation for small and medium-sized projects. If any inquiries, you are welcome to get solution from us.