Suspended substances

Finally, selective separation and dewatering of one suspended substance in a slurry containing different minerals or precipitates is possible by selectively adsorbing a magnetic material (usually hydrophobic) onto a soHd that is also naturally or chemically conditioned to a hydrophobic state. This process (Murex) was used on both sulfide ores and some oxides (145). More recently, hydrocarbon-based ferrofluids were tested and shown to selectively adsorb on coal from slurries of coal and mineral matter, allowing magnetic recovery (147). Copper and zinc sulfides were similarly recoverable as a dewatered product from waste-rock slurries (148). 

Nickel sulfate (NiSO ) exists in different states depending on its hydrated forms (where water molecules bond with ions in suspended substances). Nickel sulfate can be in the form of greenish-yellow, blue, or green crystals, depending upon the degree of hydration. It is used in nickel-plating iron and copper, as a catalyst, as a mordant in the textile industry, and as a coating for other substances. 

The water cycle in the biosphere determines the planetary transitions of various components such as aerosols, micro-organisms, and dissolved and suspended substances. 

Electric endosmose is of technical importance for the dehydration of organic, finely suspended substances containing1 very much water, for example, the drying of peat, according,... 

Flotation is a complicated process. Its separation efficiency depends not only on the properties of suspended substances the volume ratio of the gas bubbles to the suspended substances, and the retention time of the flotation tank, but also on the bubbles size. Usually, the smaller the bubbles are, the higher the flotation efficiency is. This is simply because smaller bubbles can provide larger specific surface area for particles attachment. Therefore, generation of finely dispersed bubbles is highly desired for any flotation processes. 

The operation of EF is very simple. This is another important feature for EF. By varying current, it becomes possible to create any gas bubble concentration in the flotation medium to fit the variation of the water flow rate and the suspended substances concentration from time to time. If necessary, a gas medium with very great surface area can be formed easily during EF, thereby increasing the probabilities of bubble-particle collision and adhesion and the formation of tenacious particle-bubble complexes (Mallikarjunan and Venkatachalam 1984). 

River waters carry both dissolved and suspended substances to the sea. The concentrations and absolute fluxes vary tremendously. The suspended solids load is largely a function of the flow in the river, which influences the degree of turbulence and thus the extent to which solids are held in suspension and resuspended from the bed, once deposited. Table 3 shows a comparison of average riverine suspended particulate... 

Since the dissolution rate of a loosely suspended substance will depend on the particle size and surface area of the solid, the technique of intrinsic dissolution has been developed. In this method, the solid of interest is compressed into a die and embedded in a rotational disc where only one face of the compressed solid remains exposed to the dissolution medium. Under these circumstances, the area of the solid-liquid interface must remain constant during the dissolution process. 

Straining is the simplest separation procedure for suspended substances, these being trapped by rakes or screens with smaller mesh dimensions than those of the separated material. This process is usually used for removal of the large-size floating impurities. 

Reactions in natural systems are controlled by the degree to which the equilibrium is disturbed. In this case nonequilibrium conditions have to be considered separately for the dissolved phase and the suspended solid phase. Disturbances of natural equilibria, for example, in a river, are most frequently found downstream of wastewater discharges, etc. To quantify concentration-dependent reaction rates the two concentration fields resulting from mixing must be described. This is done using known and tested models to describe turbulent diflFusion of dissolved and undissolved suspended substances (26). 

Overall liquid ground water is also a complex heterogeneous system, in which should be discerned 1) real solution 2) inert suspended substance 3) biocenose (live dispersed matter). 

Three major types of rocks are found in Earth s crust igneous rocks, formed by solidification of molten rock (e.g., basalt) sedimentary rocks (e.g., sandstone, which is cemented sand), formed by deposition of dissolved or suspended substances from oceans and rivers and metamorphic rocks (e.g., marble), formed by the action of heat and pressure on existing rocks. Figure 18.2 gives the average composition of Earth s crust. The most abundant substances in rocks are silicates, which are composed of silicon, oxygen, and positive metal ions (Section 18.5). The more than 2000 kinds of known minerals fall into a few major classes (Table 18.1). 

Water may contain mineral substances, organic compounds and gases in solution as well as undissolved (suspended) substances. Dissolved substan-... 

There are other ways of defining the partition coefficient, e.g., not as amount in solution divided by total amount in suspension, but as concentration in water relative to concentration on suspended matter. Here, Kd is set to 0.1 as a default value, which means that 10% of X is in solution and 90% is particulate. In practice, it is evident that the Kd-value is not a constant, but a variable, which depends on, e.g., (1) the given substance X, (2) lake water pH (and all cluster parameters linked to pH, such as hardness, conductivity, alkalinity, etc.), which influences the equilibrium between X and the particulate phase and the aggregation processes of the carrier particles, (3) the presence of colored substances (humus), which often have a strong affinity to many types of suspended substances (like metals, organic toxins, radioisotopes, etc.), and (4) the character of the particulate phase (if this is clays, humic matter, Fe-oxides/hydroxides, etc.). So, in more extensive ecosystem models, one would need comprehensive submodels to predict the partition coefficient. 

Ideally, for a stable suspension, the solubility of the suspended substance should be not higher than 0.1 mg/mL and the proportion of the dissolved substance should be not higher than 0.1 % of the total amount of the oral liquid. If this is not quite to be achieved, extra attention to the particle... 

Evaporation is the separation technology to separate a solvent - in most of the cases water - from a solution, emulsion or suspension by means of boiling, while the dissolved or suspended substance has no or only a slight steam pressure. 

In other cases, the concentration of the dissolved, emulsified or suspended substance is given priority. For example, for the production of condensed milk, it would be desirable to achieve a higher dry substance contents in the product. 

---