To get the most value out of extracted aggregate, it often needs to be washed clean of all impurities. Traditional washing systems, including log washers and washing drums, have long been the equipment of choice to clean material, but because they soak the material to clean it off, these machines consume large amounts of water and energy, according to W.S. Tyler.
Today, it is more important than ever to reduce this environmental impact. According to Florian Festge, president of W.S. Tyler Canada, the company’s Haver Hydro-Clean effectively cleans deleterious material from aggregate, industrial minerals and metals while reducing water consumption by up to 75 percent and energy costs by up to 15 percent over traditional washing systems.
“In addition to the energy and environmental concerns, some materials simply aren’t washable in these types of systems,” Festge said. “For example, materials caked with heavy clay are often deemed ‘unwashable’ by traditional machines.” This again is where the Hydro-Clean shines, Festge states, as its high-pressure design ensures virtually any material is washed clean, leaving more product – and profit – on the table.
An Innovative Washing Process
The Hydro-Clean washing unit removes silt and clay particles as small as 63 microns from mineral mixtures. Also, Festge said with its short retention times, the unit can process up to 400 tph, depending on model size and application. Material is continuously fed to the unit by a conveyor belt. Two adjustable water jets located above the hopper create a low pressure downstream current, which helps clean off impurities, particularly sticky material, and allow it to flow into the washing chamber.
“Material height in the hopper is constantly monitored by a laser level indicator that provides exact data to the PLC (Programmable Logic Control) unit,” Festge said. “The PLC reads the data, then regulates the material flow accordingly. It controls how fast the machine works so that consistency in production is achieved. If material volume increases, the PLC unit tells the Hydro-Clean to work faster. If the volume decreases, it tells the Hydro-Clean to work slower. If the Hydro-Clean is turned on before material is fed into the machine, it will not start, preventing unnecessary energy usage.”
No Stone Left Unscrubbed
Once inside the Hydro-Clean, material is washed by high-pressure water nozzles, located on a washing head. Utilizing up to 90-percent recycled water, the nozzles rotate at 100 rpm and spray the material at impressive pressures, up to 2,900 psi (200 bars). Featuring an angled design, the nozzles create a shoveling effect, which spreads out the material and helps to ensure every angle of the material is touched and every side washed.
According to Festge, most traditional washing systems only wash the material’s surface, while the Hydro-Clean’s high-pressure jets are able to penetrate every pore and wash the material completely. Further assisting the cleaning process are friction and shear forces resulting from the material movement around the chamber in a vortex. Traditional washing systems use only the shear forces generated between the material and washer trough by a rotating agitation implement.
“During the cleaning process, the washed material works its way down the drum and exits onto a discharge conveyor,” Festge said. “Next, the conveyor takes the material to a standard rinse screen, which removes any remaining dirt or clay as it fractionates the material. Meanwhile, the resulting dirty water flows through polyurethane screen panels installed in the sides of the washing drum, and is collected by a waste water system. The dirty water is then sent through the rinse screen and into a fines hopper, which directs it to the plant's water treatment system for recycling.”
Greening the Washing Process
Traditional washing systems are filled with water and use large amounts of energy to move the material and water at speeds fast enough to effectively clean the material. Festge says W.S. Tyler engineered the Hydro-Clean to reduce this excessive water and energy use, and provide additional green benefits over traditional washing systems.
Water Savings – Traditional washing systems, such as log washers, can use up to 900 gpm of water to clean material. Festge explains these types of units clean material in a slurry full of water. The water is used to soak the clay and carry the fines away. The Hydro-Clean only needs 200 gpm of water, using as much as 75 percent less. Inside the Hydro-Clean, water is instead used as a high-pressure tool that cuts the dirt away so large amounts are not needed to soak the material.
Recycled Water – Festge credits the Hydro-Clean’s robust filtering technology with the ability to re-circulate the used water through an operation’s water treatment system. Furthermore, re-circulated water only requires the addition of 10 percent fresh water to be used again.
Energy Savings – Power requirements for the Hydro-Clean are no higher than 300 hp (225 kW) on its largest model because, according to Festge, the water does most of the work.
Waste Reduction – Due to its superior cleaning abilities, the Hydro-Clean transforms previously “unwashable” waste piles into a salable material. Not only is this beneficial to the environment, Festge says it also translates straight from the expense side of the income statement to the revenue side, resulting in direct bottom line profits.
Compact Size – Due to its compact size and weight, overall operating and structural costs are considerably lower than with traditional washing systems – which also require more equipment and a greater footprint. The standard Hydro-Clean weighs only a total of eight tons compared to traditional washing equipment that can weigh more than three times as much. This allows for a much smaller and leaner building structure, reducing the area of influence on the environment.
Designed For Any Operation
The Hydro-Clean is available in four model sizes that produce from 20 to 400 tph, depending on the application, and fits easily into most operations without major structural changes. It removes impurities from raw material up to 6 in. (150 mm) in size using ultra-high water pressures that can reach 2,900 psi (200 bars). The distance between the washing rotor and the material bed in the Hydro-Clean is variable and allows the system to adapt to various material types. Each unit can be combined with a portable chassis for operations that need to move the unit.
Because each application and production process is unique, Festge says W.S. Tyler offers potential customers the use of a Hydro-Clean test unit. The HC350 mobile testing unit was developed to provide an on-site demonstration of washing a company’s own material, either as part of its existing process or independently. For a small fee and the cost of freight, a technician can have the test unit working within hours of arrival so customers can see how a Hydro-Clean will improve their operation.
Making an Impact
While still fairly new to North America, the Hydro-Clean has already made a global impact. According to Festge, more than 50 Hydro-Clean units are already in the marketplace. From aggregate, sand and gravel, limestone, track ballast, raw gypsum, and building rubble to diamonds, gold and lagoon sediments, it continues to produce clean product time and time again.
W.S. Tyler, www.wstyler.ca