Hydrocyclone process

To reduce oil content to levels which meet disposal standards it is often necessary to employ rather more sophisticated methods. Two such techniques which can reduce oil in water to less than 40 ppm use gas flotation and hydrocyclone processes. 

The hydrocyclone process is applicable for processing hard and soft wheat flours, and perhaps even wholemeal flour.92 In addition to its versatility in processing different wheat classes, other advantages of the hydrocyclone process compared to the Martin process include an increased yield of gluten, lower water and energy requirements, and manageable levels of effluent. To ensure the food safety of wheat starch, quality programs in many companies dictate the implementation of hazard analysis and critical control points in the hydrocyclone process.24... 

Figure 10.1 Flow diagram of the hydrocyclone process. (Adapted from reference 52)...

Some PP is collected, often inadvertently, when HDPE or PET bottles are collected and have their PP closures in place. On HDPE bottles in particular, this is problematic since HDPE and PP are not separable in common sink-fioat or hydrocyclone processes designed to separate heavier-than-water from lighter-than-water materials. Even very small amounts of pigmented PP caps cause discoloration in unpigmented HDPE streams. While PP is more readily tolerated in pigmented HDPE streams, large amounts of PP cause unacceptable decreases in performance of the recycled material. PP contamination of PET is not a major issue since the materials can be readily separated. 

The separation efficiency of a hydrocyclone has a character of probability. This is to do with the probability of the position of the different particles in the entrance to the cyclone, their chances of separation into the boundary layer flow and the general probability character of turbulent flow. Coarse particles are always more likely to be separated than fine particles. Effectively, the hydrocyclone processes the feed solids by an efficiency curve called grade efficiency , which is a percentage increasing with particle size (see chapter 3 for more details about grade efficiency). Figure 6.6 shows the process schematically the solids in the feed enter the cyclone and are... 

The hydrocyclone, commonly referred to simply as cyclone, is a nonmechanical sedimentation-type classifier (2,6,10,27) (Fig. 7). It has no moving parts or power attachments directly connected to it. The hydrocyclone has become the workhorse of most mineral processing operations because of its simplicity, short residence time, compactness, and low cost of operation. It is, however, characterized by lack of sharpness of separation. Equipment... 

Xanthates are used in a froth flotation process of soils contaminated with mercury. The soil to be treated is mn through hydrocyclones, and the slurries are flocculated, dewatered, and removed to a secure landfill. The effluent water is recycled. The process is suitable for treating industrial land sites contaminated with mercury droplets (115). 

Lynch, A.J., T. C. Rao, T.C., "Influence of Hydrocyclone Diameter on Reduced Efficiency Curves," International Journal of Mineral Processing, 1, 173 (1974)... 

This process removes the coarser fractions in the hydrocyclones. Hydrocyclones basically operate within the sand region, and if there is material that is finer than sand (material that passes a 200 mesh screen), then approximately 100 percent of that material will pass out the top. The finer fractions and the wastewater that overflow from the hydrocyclone are not treated any further. The contaminants that reside on the finer fhactions adhere fairly well to such particles, therefore, it does not make any processing sense to try and remove them. The coarser fractions then subsequently move down into the next cells. The fluid movement from right to left and the solid... 

Brayshaw, M.D., 1990. Numerical model for the inviscid flow of a fluid in a hydrocyclone to demonstrate the effects of changes in the vorticity function of the flow field on particle classification. International Journal of Mineral Processing, 29, 51. 

A second separation process reported by EBC is based on the use of hydrocyclones. Stable emulsions formed by good oil-cell-water contact and mixing can be separated continuously with hydrocyclones to obtain relatively clean oil and water. A method and an apparatus for separating a water/organic/solid emulsion, wherein the solid comprises particles having a length of about 50 xm or less, has been disclosed [267], This separation process scheme is shown in Fig. 14 and as before the separation method is envisioned as part of a BDS process. 

The second important piece in the process development is the separation scheme. Several methods were suggested, such as decanting, water extraction or fractional distillation, use of hydrocyclones, hydrophobic membrane filters, etc. In the early work at EBC, many of its patents refer to facilitating catalyst separation via immobilization, although no mention is given on how activity was impacted by that immobilization. Furthermore, there were no details on how immobilization was achieved and which were the preferred means and techniques. 

Solids. Treatment of mustard agents by the SILVER II process results in the precipitation of silver chloride, which, if not removed, could cause cell plugging. This precipitate is removed from the main circuit in a slurry underflow from hydrocyclones in the anolyte feed stream circuit. Subsequently, this slurry is dewatered in a centrifuge to approximately 50 weight percent AgCl, with the remainder of the slurry consisting of water, nitric acid, silver nitrate, and trace amounts of other materials in the anolyte loop. 

The IRS consists of the secondary polishing circuits of the SILVER II process and the associated components, including hydrocyclones, AgCl separation equipment, and the HN03 evaporator. 

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