Vacuum floating

Silicon is prepared commercially by heating silica and carbon in an electric furnace, using carbon electrodes. Several other methods can be used for preparing the element. Amorphous silicon can be prepared as a brown powder, which can be easily melted or vaporized. The Gzochralski process is commonly used to produce single crystals of silicon used for solid-state or semiconductor devices. Hyperpure silicon can be prepared by the thermal decomposition of ultra-pure trichlorosilane in a hydrogen atmosphere, and by a vacuum float zone process. 

Skimming and vacuuming floating PCP/oil from the catch basin and p>ond ... 

For low pressure pipelines that have ports open to the atmosphere, eg, sewers or closed effluent culverts, samplers are designed to sample through manholes. In a typical system, the Hquid is lifted through a suction line into the sampling chamber under vacuum. When filled, the vacuum shuts off, and the sample drains into a sample jar. A secondary float prevents any Hquid from reaching the vacuum pump. The suction line then drains by gravity back to the source. 

Anaerobic Contact. This process can be considered as an anaerobic activated sludge because sludge is recycled from a clarifier or separator to the reactor. Siace the material leaving the reactor is a gas—Hquid—soHd mixture, a vacuum degasifier is required to separate the gas and avoid floating sludge ia the clarifier. 

In contrast to vacuum flotation, dissolved-air flotation units can be operated on a continuous basis by the application of pressure. This consists of pressurizing and aerating the process stream and introducing it into the flotation vessel that is maintained at the atmospheric pressure. The reduction of pressure results in the formation of fine air bubbles and the collection of fine particulates to be floated and removed as sludge. 

Two processes, referred to as sputtered and pyrolitic, were developed to produce large volumes of quality, low-e coated glass. Pyrolitic coatings are incorporated into float glass production and tend to be more durable. Sputtered systems use a stand-alone vacuum deposition process to produce coatings that are have lower emissivities but that are softer and need more protection than pyrolitic coatings. 

Condenser tail pipes, used tvith any condenser, are sealed with a 34-foot leg into a sump, or with a condensate pump operating under vacuum on suction. With surface-type condensers, the level may be sealed in a receiver with a float or other type of level control. 

This is a unit operation process where air bubbles, as gas, are used to remove solid or liquid particles from the liquid wastewater. The air bubbles are often trapped in the morphology of the suspended particles and as a result of buoyant forces, the particles move up and float on the surface where they are skimmed out. The common flotation methods include dissolved air, air flotation, vacuum flotation, and chemical additives.3... 

Since boron trichloride reacts with many lubricants to form hydrogen chloride, the diboron tetrachloride synthesis is carried out in a grease-free system. A mercury float-valve vacuum system4 depicted in Fig. 15 is employed here. The U-traps have a capacity of 50 ml. without plugging and tubes A and B have... 

Sites suitable for conventional SVE have certain typical characteristics. The contaminating chemicals are volatile or semivolatile (vapor pressure of 0.5 mm Hg or greater). Removal of metals, most pesticides, and PCBs by vacuum is not possible because their vapor pressures are too low. The chemicals must be slightly soluble in water, or the soil moisture content must be relatively low. Soluble chemicals such as acetone or alcohols are not readily strippable because their vapor pressure in moist soils is too low. Chemicals to be removed must be sorbed on the soils above the water table or floating on it (LNAPL). Volatile dense nonaqueous liquids (DNAPLs) trapped between the soil grains can also be readily removed. The soil must also have sufficiendy high effective porosity (permeability) to allow free flow of air through the impacted zone. 

It is advantageous to generate bubbles of micron-size when the particles to be floated are very small. The generation of such bubbles is almost impossible in conventional equipment which relies on mechanical means of breaking down the gas. If air, or another gas, is dissolved under pressure in the suspension before it is introduced into the cell, numerous microbubbles are formed when the pressure is reduced and these then attach themselves to the hydrophobic particles. Similar effects can be obtained by operating the cells under vacuum, or producing gas bubbles electrolytically. Dissolved and electro filtration are discussed later. 

Some asbestos materials can break into small fibers that can float in the air, and these fibers can be inhaled. These tiny fibers are small, cannot be seen, and can pass through the filters of normal vacuum cleaners and get back into the air. Once inhaled, asbestos fibers can become lodged in tissue for a long time. After many years, cancer or other sickness can develop. In order to be a health risk, asbestos fibers must be released from the material and be present in the air for people to breathe. A health risk exists only when asbestos fibers are released from the material or product. Soft, easily crumbled asbestos-containing material, previously defined as friable asbestos, has the greatest potential for asbestos release and therefore has the greatest potential to create health risks. 

To size the two species however, it is necessary to separate them. A sink-float technique has been developed to separate the two. A carbon tetrachloride - tetrabromoethane mixture having an SG about 2.5 was used. The dry crystal mixture is added to the dense organic liquid, then put under vacuum to remove entrapped air bubbles. The suspension is then centrifuged for several hours to separate out the gypsum which floats and the hemihydrate which sinks. Tests on synthetic mixtures showed that a very clean separation is possible. 

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