The Aran continuous mixing pugmill plant is state of the art. It is a volumetric computer controlled twin shaft pugmill plant. Its on board power is a Cat 3406B (360 HP). This unit provides the power to the hydraulic system which powers the mixing chamber, the feed belts, bag house, discharge belt and gob hopper. The Cat 3406B also provides air for the bag house and the electricity for the on board computers and Ramsey Belt scale.
This plant has a rated capacity of 1,000 tons per hour. This rate will vary depending on the physical properties of the soil, amount and type of additive, and the desired production rate. Below is a list and description of the major components as shown on the schematic on the previous page.
- Self-erecting 1,340 cubic foot silo.
The silo is filled pneumatically from bulk tankers. Additives such as cement, fly ash, lime and bentonite are blown into the silo. A self-erecting auxiliary silo may be set up next to the plant if more than one type of additive is required. The auxiliary silo operates off the plant’s power and is controlled by the plant’s computer system. These silos are equipped with a Dalamatic DLM/V 10 dust control system.
- 16 cubic yard material feed hopper.
This hopper is fed with the soil(s) to be processed. It may be divided so as to accommodate two types of soil or aggregate. The hopper and its two 24-inch belts may be fed one of three ways. First, a front-end loader can feed the hopper directly by building a ramp perpendicular to the hopper. Second, material may be conveyed in the hopper. Third, a screen can process directly into the hopper. Experience has shown that screening directly into the hopper is a good method to limit the handling of material, but, due to screen capacity, it is often the limiting factor concerning maximum production of the mixing plant.
- Twin shaft 66 paddle pugmill.
The pugmill is designed to achieve a violent mixing action throughout its 14 fool length resulting in a well mixed homogeneous product. This type of mixing, with no slump or low moisture products, is more effective than a drum type mixer that merely folds the product.
- Hydrostatic cleated belt additive feeder.
The additive is fed to the pugmill at the beginning of the mixing operation by means of the computer controlled cleated belt. Accuracies of better than plus/minus 2% of the design proportioning of the additive are achieved.
- 1,330 gallon water tank.
Water required is determined by the mix design and the native water in the material to be mixed. Water is fed from an outside source into the plant’s onboard water tanks. This water is fed at the design rate into the mixing chamber by three, 2 inch hydraulic pumps which are computer controlled.
- 30-inch discharge belt.
The mixed product is discharged from the pugmill on this conveyor belt. The finished product is continuously and cumulatively weighted on a Ramsey belt scale.
- 1.5 yard gob hopper.
The gob hopper is utilized to interrupt the continuous flow of mixed material allowing trucks to enter and exit the loading area. If trucks are used to transport the mixed material away from the plant, the direction of travel of the trucks should be with the driver’s side closest to the plant so that he/she may see the plant operator. The gob hopper maybe left open continuously so that a conveyor may be used to remove the finished product from the mixing plant.
A computer controlled pump is also on the plant that may be used to add a liquid additive. The overall weight of the plant with additive, aggregate, and water is approximately 350,000 pounds.