Elite Group - Prometal
  Process of production of concrete blocks  

Basically, the production of concrete blocks with Prometal equipment is based on a stationary block-making machine, handling and cubing system (with different options supplied by Prometal within its range of models).

Prometal stationary presses offers a number of advantages:

- Better quality of the products (better vibration, curing of products indoor, saving the task of watering).
- Less area needed.
- Better working conditions (inside hangar).
- Higher degree of automation, thus needing less labour force.
- Etc.

Concrete elements

Moreover, all Prometal’ installations are mastered by user-friendly PLC with terminal of data access (computerizing as an option), that controls all the parameters of the production process (dosing and feeding of raw materials –recipes for each product are inserted in the memory-, vibration of press, etc.) in automatic mode.

The production process starts in the batching plant, where the concrete is made to feed the press. As raw materials, usually three main aggregates are used –one coarse aggregate and two sands - to ensure better overall grading of the concrete mix. Ordinary Portland cement is predominantly used, but the inclusion of cementitious filler and chemical admixture improves mix workability and colour dispersion within the mix.

The batching plant is usually tailor made for every customer, depending on a number of factors (situation of the plot of land where it will be located (flat or steep, area available, etc.), traits of the supply of aggregates (periodicity of delivery and so on) and of course the liking of the manufacturer. In the standard Prometal system the hoppers are made on concrete and the idea is that the trucks unload the aggregates directly to them (this implies regular supply). The hoppers can be made of metal as well.

An alternative system consist in the works being served by three aggregate storage bays, from which the aggregates are collected by a loading shovel, and loaded into an external aggregate feed hopper. From there, the three aggregates are transported into one of several internal aggregate holding bins, but there are many others systems.

The covered facility lessens the impact of material moisture content variations. When required for production, the aggregates from these bins are fed onto a belt. If the dosing is made by volume, there is a system to measure the time that the feeders are open, but also a weigh belt can be used to dose by weigh. In both cases thence the aggregates fall into the feed skip of the mixer (also a conveyor belt can be used), which is then hoisted up and discharged into the mixer.

In the mixer the cement and water are added to the mixture (as said it is possible to add some pigments or liquid chemicals to improve workability or the properties of the product). Once the mixing process has been completed, the fresh concrete is discharged onto a conveyor belt underneath the mixer, and carried up and into the holding hopper of the block machine itself. At the start of the next production cycle, the mix is discharged into the filling box, which passes to-and-fro across the top of the mould, as it feeds in its load.

There is where the products are shaped and made thanks to a small degree of compaction but is most important the effect of a controlled heavy vibration (which mainly stem from a vibration table underneath) that forms the new blocks on a production pallet. As they leave the press machine, the blocks can pass the first quality inspection station (visual checks).

The blocks are then carried from the block-making machine and into the elevator, from where they will be collected and carried to curing chambers, by means of a fork lift in semi-automatic models or of an automatic finger car in the fully automated plants. When this finger car is full, it carries its load of blocks to the in-feed point at the entrance to the curing chamber that is currently being filled, and feeds them onto the 10 levels of the racking system.

The curing facility has a capacity equal to 24 to 48 hours production (depends on different factors). There are a number of separate tunnels (this will determine the autonomy of the plant). After leaving the fresh blocks for curing, the finger car goes to another tunnel and picks the pieces that are already dried, to take them to the lowerator system and from here onto a conveyor for the final production stages. As they are carried from the lowerator, the pallet-loads of blocks can pass a second quality control station, on their way into the cubing area.

After cubing onto wooden pallets (depending on the model, the cuber will be semi or fully automatic), the newly-built cubes then pass through a banding station, where a banding machine wraps 4 polyester bands round each pack, at the same time that makes a shrink-wrapping movement (this stage is optional and this machine is not manufactured by Prometal).

The pallets then pass out of the production building into the “out-feed” area, where a fork-lift truck (or clamp truck, if there are not pallets) lifts off (one or two packs at a time) and takes them to a pre-designated area within the stockyard, where the product is stacked in bays awaiting the moment when they will be load into trucks to be delivered to the customers.

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