1. Introduction and application of LECA (light expanded clay aggregate)
LECA (light expanded clay aggregate) is a versatile material. Some characteristics of LECA are: lightness, thermal
insulation by low conductivity coefficient (as low as 0.097 W/mK), soundproofing by high acoustic resistance, moisture impermeable, incompressible under permanent pressure and gravity loads, non-decomposition against severe condition, fire resistant, Ph of nearly 7, freezing and melting resistance, easy movement and transportation, lightweight backfill and finishing, reduction of construction dead load and earthquake lateral load, perfect sweet soil for plants, material for drainage and filtration.
Because of these advantages of LECA, it is utilized in an increasing number of applications.
LECA common uses are in concrete blocks, concrete slabs, geotechnical fillings, lightweight concrete, water treatment, hydroponics, aquaponics and hydroculture.
2. How to produce LECA
LECA is usually produced in different sizes commonly 0-4 mm, 4-10 mm, 10-25 mm and densities of 250, 280, 330, and 510 kg/m3.
The traditionally Lightweight expanded clay aggregate (LECA) 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.
As the LECA production technology developed, to exploit the clay resource is not benefit for the harmonious relationship between human and nature, so our company working so many many years and successfully developed a fully automatic LECA production line with several patent, which could adopt the tradition material: clay, shale, slate, it also to use the solid waste like flyash, coal gangue, tailings, municipal sludge, sea and river sludge to produce the high quality LECA, by which it could realize recycling the solid waste. By this LECA plant, we could produce several kinds of LECA: LECA used for building materials, LECA for garden plants and flowers.
3. LECA manufacturing technique
No matter which kind of raw material adopts, the general process are: homogenization of raw materials, granulation, sniter and cooling. According to the classification of raw material, the LECA produce process can be divided into: 3.1. Plastic method: which is suitable for clay and clay raw material, and its process is as follows: clay -plasticizing, homogenizing - granulating - roasting - cooling - finished products. 3.2. Balling method: which is suitable for fly ash or other pulverized raw materials, and its process is as follows: fly ash- homogenizing, balling, granulating - roasting - cooling - finished products. 3.3. Grinding powder into ball method: which is suitable for raw materials of shale, clay shale and coal gangue, and here is the process: drying- grinding - prewetting - granulating - roasting - cooling - finished products, additive. 3.4. Crushing (dry) process: which is suitable for raw materials of shale, and the process is as follows: shale - crashed and classified - roasting - cooling - finished products. 3.5. Fuel: according to the situation of local fuel supply, use bituminous coal, heavy oil or gas.
4. The Capacity of ZK LECA production line
Depends on local LECA requirements and capital available, the LECA production line capacity could be 20,000~30,000 m³ per year, 50,000m³per year, 100,000m³ per year, 150,000m³ per year, 200,000m³ per year.