Evaporative Sulfate Salts

Hence, mine wastes, tailings, and smelting byproducts can contain a wide variety of minerals, including minerals that are bioreactive (such as acid-generating sulfides and evaporative sulfate salts), minerals that contain potentially bioaccessible heavy metals and metalloids (lead, cadmium, arsenic, mercury, zinc, copper, nickel, uranium, molybdenum, antimony, etc.), and minerals that are biodurable (such as quartz and, in some deposit types, asbestiform silicates). 

Evaporative Sulfate Salts as Temporal Sinks of Metals and Acidity... 

The production of table salt from seawater, by the use of ED to concentrate sodium chloride up to 200 kg/m3 prior to evaporation and salt crystallization, has achieved a certain commercial importance, especially in Japan and Kuwait, even if it seems to be highly subsidized (Strathmann, 1992). The key to the success of this technology has been the low-cost, highly conductive membranes with a preferred permeability of monovalent ions. This allowed chloride ions to be cumulated in the concentrated stream, while Ca2+ and Mg2+ ions and sulfates were quite totally rejected in the diluting stream. 

Crystalline N,N-dimethyl desacetyl VLB glycinate was dissolved in a mixture of methanol and water. The pH of the solution was adjusted to about 1.8 with 1% sulfuric acid. Evaporation of the resulting solution to dryness in vacuum yielded N,N-dimethyl desacetyl VLB glycinate sulfate as a residue. The residue was crystallized from a mixture of methanol and ethanol. MP 284-285°C. Nuclear magnetic resonance and infrared spectra of sulfate salt were entirely consistent with the assigned structure. 

Soluble metal sulfate salts formed by the evaporation of ARD. 

This process also transfers heat from the flue gases to the black liquor so that it leaves the last stage of evaporation hot. At this point, it is referred to as strong black liquor. Addition of make-up chemicals, either sodium sulfate ( salt cake ) or sulfur as necessary is carried out at this stage to replace any losses of sodium and sulfur occurring elsewhere in the process. In fact, sulfate process is synonymous with kraft process because the primary make-up chemical requirement of the kraft process is sodium sulfate, although sodium sulfate is not an active constituent of kraft pulping liquor. 

In this second step of analysis, the charred substance obtained by the first procedure is incinerated to evaporate all the carbon as carbon dioxide. This can be difficult to obtain if the substance to be examined was not fully charred before incineration. The residue obtained should be a well-defined and relatively stable mixture of the sulfate salts of the cations originally present, typically sodium sulfate and potassium sulfate. This gives a more reproducible result than if the test were based on a residue of the salts originally present since many of them are not stable enough to survive the ashing procedure. This applies, for example, to many carbonates, but even sulfate salts can be degraded if prolonged and excessive heat is applied. 

The industrial crystallization process examined is outlined in Figure l.The filtered fermentation broth was fed to the vacuum evaporator and concentrated to 28 g/dl then the pH was adjusted within the range of 1.7 to 2.0 with sulfuric acid. When this solution was cooled continuously through a two-stage crystallizer whose temperature were 40 and 25 C, the pillar form crystals of the sulfate salt of l phenylalanine formed and were easily separated by centrifugation. 

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