AAC Plant

RAW MATERIAL PREPARATION

A ball mill wet-grinds the quartz sand with water to a sand slurry. The sand slurry is stored in slurry tanks and pumped into the slurry weighing hopper in the mixer tower. The binders (lime, cement and anhydrite) are stored in silos. It is also possible to mill the anhydrite together with the sand in the ball mill. The aluminum powder or paste is prepared in a separate building where it is dispersed in water.

All the components are accurately weighed and are released into the mixer in a pre-defined order. The LAXMI recipe and temperature control system constantly monitors this process.

LAXMI also has the knowledge and the experience to produce AAC with alternative raw materials, for example with fly ash

CASTING, RISING/PRE-CURING AND MOULD CIRCULATION

The mould consists of four fixed sides and one detachable platform. The inner mould surfaces are covered with demoulding release oil before casting. This oil is applied either manually. The mix is then poured into the mould. A transfer platform transports the filled casting mould to the closed and heated pre-hardening area, also called the Pre-curing room. Due to the alkaline reaction of the aluminium in the slurry, many small bubbles develop in the compound. At the same time, the cake begins to harden. After a waiting time of approx. 2 – 3 hours, the preset "green strength" (cutting strength) is reached. The waiting time depends on the temperature in the Pre-curing room, but also on the quality of the raw materials used and the chosen recipe.

TILTING

The tilting crane tilts the mould by 90°. The Tilting crane unlocks the mould and removes the mould body, so that the cake remains on Side plate for cutting. This tilting system has proven to be the safest method for tilting the cake into the vertical cutting position, as the cake is remaining on Side plate for the cutting process.

CUTING

The cake in cut by high precision cutting machines. Cutting is done by pneumatically tensioned cutting wires. As the aerated concrete block stands upright, it is possible to use short cutting wires. The horizontal cutter and vertical cutter cut the block length and width. All waste material generated in the cutting process is collected in a basin underneath the cutting line, recycled, and returned to the production process.

AUTOCLAVING

After cutting, the green cakes are grouped on steam car by crane. The aerated concrete is hardened under steam pressure in special, sealed pressure vessels, the autoclaves, thereby achieving its final strength. The steam pressure is approx. 12 bar, the temperature approx. 192° C. Usually, the hardening time is between 10 and 12 hours. The used steam for the hardening process in the autoclaves is generated in a steam boiler plant. Usually, high-capacity steam boilers that are operated by coal or wood are used to generate the steam.

UNLOADING AND PACKAGING

After autoclaving is completed, the cakes are destocked and unloaded from the Steam car. LAXMI offers a large variety of packaging solutions, ensuring that the finished products are packed according to local market requirements. Usually blocks will be delivered as packs on wooden pallets, strapped and/or covered in foil.

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