Construction Mirror Article detail

SAND WASHING PLANT MODELS

Sand Washing comes in many forms and covers a range of feed and products produced, including construction aggregates such as concrete, asphalt, mason, mortar, and plaster sands; sports sands such as for golf courses, ball parks, and race courses; industrial sands, such as glass, filter, foundry, and frac; specialty sands and materials such as anti-skid, roofing granules; deligniting/organics removal; and soils washing for environmental projects.

 

HOW SAND WASHING PLANTS WORK

Sand Washing Plants covers a variety of processes to get the sand from the raw state to a finished state. This process can include: Feed Preparation - Before the raw feed can be processed, it must be prepared using a combination of Attrition Cells, Blade Mills, Coarse Material Screw Washers, Log Washers and Rotary Scrubbers. The objective is to bring all materials into suspension, essentially breaking down any clays and clay-bound materials and removing superficial surface contamination.

 

Sizing – Prior to and immediately after the feed preparation step, the raw feed must be screened into fractions appropriate for both the downstream process and the products to be produced. Vibratory Screens are typically used. Pumping – Centrifugal Slurry Pumps are the preferred means by which slurry is transferred from one plant/process to the next. Pumps are also used for effluent disposal. Although there can be resistance to using a pump over a gravity-fed unit, a gravity-fed unit may not be able to capture saleable materials. These losses go straight to waste and will end up costing you money in the long term.

 

Desliming - If a significant amount of liberated ultra-fine material is present in the feed, it is typically desirable to remove this deleterious fraction before classification. Classification efficiency can be adversely impacted by high levels of suspended clays, leading to losses of saleable materials and dirty products. Cyclones are the preferred desliming device due to their high shear and efficient classification. Feed Regulating Sumps are also very appropriate especially where there are high volumes such as would be found in dredging applications. Their controlled overflow can reduce the power consumption for pumping to downstream classification. Occasionally, desliming or simply washing is all that is needed to create the final product by removing the <75μm (<200 mesh) down to a certain level, such as 3-5% passing.

 

Classifying – This is the process of separating particulates from one another based on either size or specific gravity. In sand washing, this applies to the <4mesh (<5mm) particulates. The procedure may involve making single sharp separations with our Hydrosizer™, or multiple size classifications with our Classifying Tanks. Where a specialty sand is being produced, such as for glass, frac, sports, filter, foundry, etc., a Hydrosizer™ provides the accuracy needed for the splits in product gradation. Cyclones and Separators™ are also classification devices operating in the 140mesh (105μm) and finer size separation range typically finer than that where a Hydrosizer might be used.

 

Densifying and Dewatering – Certain types of equipment, like Hydrosizers and Attrition Cells, require dilute slurry to be concentrated. Cyclones or Separators™ are most commonly used for this purpose. Separators™ are especially suited for this duty with the ability to dial in and

under flow density. In the case of dewatering, Fine Material Screws, Dewatering Screens or Separators™ are the most common devices. The lowest moisture content, by far, is obtained with a Dewatering Screen. With improved safety (less cleanup around the conveyors), better housekeeping (almost no water drainage from the stockpile) and more immediate availability, Dewatering Screens have become the equipment of choice for final product dewatering.

 

Effluent Treatment – Water is a very valuable commodity, so it is becoming a requirement to

 a water recovery circuit as part of any permitting process. The device most common for this purpose is a Thickener. In most cases, 85% of the process water can be recovered for reuse. The most cost-effective storage method is a dedicated water tank to reduce the percolation and evaporation losses associated with ponds. These tanks also save on the power requirement to pump the water out and back.

 

Waste Solids Management – While Thickeners can recover process water, the underflow is relatively dilute and is typically be pumped to containment ponds. To finish off the sand washing process and have the waste solids in a conveyable and stackable condition, Filter Presses are typically employed.

 

Sampling - Every system requires monitoring and sampling to provide the best results. McLanahan can design a sampling system up front to focus on the key areas. The ability to react faster to process changes helps eliminate waste, improve product quality and troubleshoot problems.

 

5 Key Points Of Sand Washing Machine Selection

In sand production line, especially in wet sand production line, sand washing is an essential part in order to improve the quality of finished sand, and sand washing machine is needed for sand washing. The sand washing machine can wash away the soil and impurities on the surface of the sand, and at the same time destroy the water vapor layer covering the sand, so as to facilitate dehydration, play the role of efficient sand washing and cleaning, and improve the quality of the finished sand.

 

Types of sand washing machine

The common types of sand washing machines on the market include spiral sand washing machines and impeller sand washing machines. Spiral sand washing machine The spiral sand washing machine mainly stirs the sand and gravel through the spiral device in the equipment, so that the sand and gravel are cleaning and screening effect of the sand and gravel. In terms of type, it can be divided into two types: single-spiral sand washer and double-spiral sand washer. It is mainly suitable for washing, grading and impurity removal in metallurgy, building materials, hydropower and other industries, especially suitable for construction sand and road construction sand.

Impeller sand washing machine Impeller sand washer is claso called wheel bucket sand washing machine. The sand and gravel in the wheel bucket sand washing machine are turned over under the drive of the wheel bucket, and grind each other to remove impurities on the surface. At the same time, add water to the inside of the sand washing machine to form a strong water flow, and take away the washed out impurities and other foreign objects with small specific gravity in time. The clean sand and gravel are taken away by the blades and poured into the discharge tank trough from the rotating impeller, thus completing the cleaning of the sand and gravel. It mainly includes single-row wheel bucket, double-row wheel bucket and three-row wheel bucket sand washing machine. It often forms a high-quality sand production line together with a sand making machine, which is used in transportation, chemical industry, mining, water conservancy and hydropower and other fields.

 

Difference between spiral sand washer and impeller sand washer Appearance structure The overall structure of the wheel bucket sand washing machine is relatively simple. There are fewer wearing parts in the equipment, and after the installation is completed, its occupied area

is small. In order to reduce the phenomenon of bearing damage caused by water, sand and pollutants, the wheel type sand washing machine has designed a structure in which the impeller drive bearing device is isolated from water and sand, thereby greatly reducing the failure rate of the equipment.

 

The spiral sand washer has a slender body and a horizontal structure, which makes the structure simpler. But it is not as convenient as the wheel sand washer in the installation arrangement. Applicable material particle size The wheel bucket sand washer is generally used to clean materials of about 5mm. And the spiral sand washing machine can not only clean the large size of the stone, but also the smaller size of the material.

 

The loss of sand and gravel

The wheel bucket sand washing machine consumes less water during the sand washing process, and the loss of fine sand and stone powder is small, so that the sand grade and fineness modulus of the washed sand and gravel can meet the standard requirements. In comparison, the sand and gravel loss of the spiral sand washing machine is relatively large during the sand washing process. Cleanliness of the washed sand The cleanliness of sand washing refers to the

quality of finished sand after washing. During the cleaning process, the sand and gravel in the spiral sand washing machine are turned over and cleaned more times, and the cleaning is more thorough, so the quality of the finished sand and gravel is better.

 

Cleaning capacity

The cleaning capacity of the spiral sand washing machine is relatively strong, and it can effectively clean the sand with serious mud impurities. It is often used in large-scale sand production lines. The production capacity of the wheel sand washer is smaller than that of the spiral sand washer, so it is more suitable for small and medium-sized sand production lines.

 

Water consumption

The wheel bucket sand washing machine does not need to use too much water during the sand washing process, and the loss of fine sand is small. However, the water consumption of the spiral sand washing machine is relatively large, and the sand and gravel are lost more.