Separation process solids/liquid

Flotation is a solid-liquid separation process, that transfers solids to the liquid surface through attachment of gas bubbles to solid particles. Flotation processes are used in the processing of crushed ores, whereby a desired mineral is separated from the gangue or non-mineral containing material. Various applications in solid separation processes are also in use in waste treatment. 

Svarovsky L (1985) Solid-liquid separation processes and technology. Elsevier Science Pub, Amsterdam... 

SVAROVSKY, L. (1985) Solid-Liquid Separation Processes and Technology (Elsevier). 

Henry JD, Lawler LF, and Kuo CHA, A solid/liquid separation process based on crossflow and electrofiltration, AIChE J. 1977 23(6) 851-859. 

The solids-liquid separation process can be accomplished by filtration or centrifugation. Centrifuges magnify the force of gravity to separate phases, solids from liquids or one liquid from another. There are two general types of centrifuges ... 

In general, flocculants are used in solid-liquid separation processes such as thickening and filtration. Inorganic salts are also used sometimes to aggregate fine particles. Flocculation technique has been developed further for special applications of selective flocculation, selective dispersion and agglomeration flotation. 

Use of Particle Size Distribution Measurements for Selection and Control of Solid/Liquid Separation Processes... 

Using the same hypothetical particulate suspension as in Figure 2, the relative distribution of the total surface area concentration as a function of size for values of j3 ranging from 1 to 5 is shown in Figure 3. If > 3, the total surface area concentration of the particulate fraction resides predominately in the fine-size fractions below 10 /x.m. Control of the concentration of an adsorbed contaminant would thus require removal of fine-sized particles by appropriate solid/liquid separation processes. If, however, < 3, removal of coarser particulates (1 > 10 /x.m) may satisfy the effluent standards. The selection of solids/liquid separation processes will thus depend, in part, on the shape of the size distribution function, as reflected by the value of p. 

When the required particulate removal eflBciency has been determined for each size fraction in the distribution, the technical feasibility of available solids/liquid separation processes must be evaluated. Such a screening procedure will provide the framework for determining the extent of analytical modeling or pilot plant studies needed to develop process design criteria. The solids/liquid separation processes used in water and wastewater treatment exploit the physical-chemical properties of the particulates to achieve rapid and therefore economical separation from the treated water. Microscreening devices remove most particulates with at least one dimension larger than the minimum opening in the... 

Figure 4. Solids/liquid separation process selection diagram. Mass concentration isopleths computed assuming spherical particles, specific gravity of 1020 kg m. (Criteria for region boundaries discussed in text.)...

These results have important implications for process control of solids/liquid separation processes. Because many suspensions in natural waters have particle size distributions with p > 3 (see Table II), presently available particle counters will not detect particulates that dominate the surface area concentration. Light-scattering devices may be needed to monitor the influent raw water supplies. However, if p values are less than 3 in effluent streams from solids/liquid separation processes, particle counters could be used for process monitoring and ultimately, process control. 

The eflBciency of solids/liquid separation processes for reduction of trace contaminants (such as heavy metals) and toxic organic compounds associated with the particulate fraction could be estimated if the chemical composition of the particulates as a function of size were known. However, such data are scarce and of questionable accuracy. As a first approximation, the distribution of an adsorbed constituent between various size classes in the particulate fraction can be estimated from a knowledge of the power-law coeflBcient. This combined with performance models of solids/liquid separation processes should provide an improved basis for process selection to meet increasingly stringent standards for water and wastewater treatment. 

Particle counters also show promise for process control and performance evaluation, particularly in low-turbidity waters. Applications include more accurate evaluation of pilot plant studies and more sensitive control of particulate separation processes. However, when the power-law coefficient, p, is greater than 3, submicron particles, which escape detection with available counters, may control the magnitude of the total surface area concentration and the light-scattering properties of the particulate. It is likely that accurate process control and monitoring of solids/liquid separation processes will require both turbidimetric and particle size distribution measurements. Particle counting appears most promising as a feedback control sensor. 

The treatment of wastes and water supplies primarily involves the removal of particulates and, therefore, is accomplished by solid-liquid separation processes. However, present design procedures for such treatment systems do not utilize or even recognize the importance of the physical properties of particulates in solid-liquid separation. In fact, until very recently, eflForts at measuring particle size in wastewaters and raw water supplies have been very limited. Among early eflForts, the investigations at Rutgers University (3,4,5,6) are especially notable. Very recent renewed interests in particle size determinations have used Coulter, Hiac, and Zeiss Videomat particle counters (7,8,9). 

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