Alkaline carbonates

Uranium ores are leached with dilute sulfuric acid or an alkaline carbonate [3812-32-6] solution. Hexavalent uranium forms anionic complexes, such as uranyl sulfate [56959-61-6], U02(S0 3, which are more selectively adsorbed by strong base anion exchangers than are other anions in the leach Hquors. Sulfate complexes are eluted with an acidified NaCl or ammonium nitrate [6484-52-2], NH NO, solution. Carbonate complexes are eluted with a neutral brine solution. Uranium is precipitated from the eluent and shipped to other locations for enrichment. Columnar recovery systems were popular in South Africa and Canada. Continuous resin-in-pulp (RIP) systems gained popularity in the United States since they eliminated a difficult and cosdy ore particle/leach hquor separation step. 

Silver Carbonate. Silver carbonate, Ag2C02, is produced by the addition of an alkaline carbonate solution to a concentrated solution of silver nitrate. The pH and temperature of the reaction must be carefully controlled to prevent the formation of silver oxide. A suspension of Ag2C02 is slightly basic because of the extensive hydrolysis of the ions present. Heating soHd Ag2C02 to 218°C gives Ag20 and CO2. 

Where sodium bicarbonate is present (as when MU water pretreatment includes a water softener), given enough time and temperature it decomposes to form hydrate alkalinity, carbon dioxide, and water ... 

If it is heated in presence of alkaline carbonates, it becomes incandescent and forms carbon monoxide. 

Because of its strong acid character sulphuric acid can decompose alkaline carbonates, violently forming a huge amount of carbon dioxide. Emissions are possible if the mixture is made without using any protection. The container can detonate if closed. 

Finally, it reacts dangerously with metal carbonates attempts to put out calcium fires with powders containing alkaline carbonates give rise to explosions. 

Titanium becomes incandescent if it is mixed with alkaline carbonates or edkaline nitrates. But in this latter case if the cation is ammonium, there is a detonation. However, detonation of a device containing potassium nitrate into which powdered titanium had been thrown has been observed. 

Reaction of an alcohol over basic catalysts favors dehydrogenation to give the corresponding carbonylated derivative. This reaction has been studied for propan-2-ol over a series of alkaline carbon catalysts, under the action of conventional heating and MW irradiation (Scheme 7.5) [17]. 

The density of the corrosive current of jamesonite in NaOH solution is basically the same as that in Ca(OH)2 solution, but it is minimal in Na2C03 solution, about a fraction of the fourth of the former. There are obvious appearances of passivation and its breaking-down in strong polarization area in NaCOa solution Because COj ion is easier to form insoluble alkaline carbonate than OH ion, the carbonate salts are passive on the mineral surface to inhibit oxidation reaction. 

Drugs that may affect aspirin include activated charcoal, ammonium chloride, ascorbic acid or methionine, antacids and urinary alkalinizers, carbonic anhydrase inhibitors, corticosteroids, and nizatidine. Drugs that may be affected by aspirin include alcohol, ACE inhibitors, anticoagulants (oral), beta-adrenergic blockers, heparin, loop diuretics, methotrexate, nitroglycerin, NSAIDs, probenecid and sulfinpyrazone, spironolactone, sulfonylureas and exogenous insulin, and valproic acid. 

Since the complete story of carbon would be a history of organic chemistry, asphalt, carbonate rocks, alkaline carbonates, fuels, foods, plant and animal nutrition, photosynthesis, and respiration, the following brief sketch can merely suggest the magnitude of the subject. 

Figure 9.29 Membrane formation by meteoritic amphiphilic compounds (courtesy of David Deamer). A sample of the Murchison meteorite was extracted with the chloroform-methanol-water solvent described by Deamer and Pashley, 1989. Amphiphilic compounds were isolated chromatographically on thin-layer chromatography plates (fraction 1), and a small aliquot ( 1 p,g) was dried on a glass microscope slide. Alkaline carbonate buffer (15 p,l, 10 mM, pH 9.0) was added to the dried sample, followed by a cover slip, and the interaction of the aqueous phase with the sample was followed by phase-contrast and fluorescence microscopy, (a) The sample-buffer interface was 1 min. The aqueous phase penetrated the viscous sample, causing spherical structures to appear at the interface and fall away into the medium, (b) After 30 min, large numbers of vesicular structures are produced as the buffer further penetrates the sample, (c) The vesicular nature of the structures in (b) is clearly demonstrated by fluorescence microscopy. Original magnification in (a) is x 160 in (b) and (c) x 400.

Szymanski, J. T. Scott, J. D. 1982. A crystal structure refinement of synthetic brannerite, UTi206, and its bearing on rate of alkaline-carbonate leching of brannerite in ore. Canadian Mineralogist, 20, 271-279. 

If 100 parts of this carbonate, dissolved in nitric acid and separated by the alkaline carbonates, gives us 100 parts of artificial carbonate, and if the base of these two combinations is the black oxide, we must recognize that invisible hand which holds the balance for us in the formulation of compounds and fashions properties according to its will. We must conclude that nature operates not otherwise in the depths of the world than at its surface or in the hands of man. These ever-invariable proportions, these constant attributes, which characterize true compounds of art or of nature, in a word, this pondus naturae so well seen by Stahl all this, I say, is no more at the power of the chemist than the law of election which presides at all combinations. From these considerations is it not right to believe that the native carbonate of copper... 

Alkaline carbon-steel vessels can be used, though stainless steel is better. 

There can be no doubt that the nitrum of ancient writings must have been in some cases an alkaline carbonate, which in their nomenclature was confused with saltpetre. It is not known when saltpetre was definitely recognized as something different from the ordinary nitrum. It is commonly supposed that saltpetre was a component of Greek fire invented near the end of the seventh century. The first definite reference to saltpetre appears in literature in connection with the preparation of gunpowder. Albertus Magnus and Roger Bacon, of the thirteenth century, both refer to this salt, and probably both derived their information from... 

Py rodialites were expls based on K chlorate and coal tar, but the tar was previously purified to remove the acids. In order to take care of acidity which could develop in storage, some alkaline carbonate or bicarbonate was incorporated. Some charcoal and other ingredients could also be incorporated and part of chlorate (or even total) could be substituted by other oxidizers, such as nitrates, perchlorates, bichromates, or permanganates Following are some rypical examples of Pyrodialites ... 

Tetrapositive Pr4+ and Tb4+ are quite stable in strongly alkaline carbonate solutions. Thus electrolytic oxidation for three hours of 2-5.5 mol dm-3 aqueous M2CO3 (M = K or Cs), 1 mol dm-3 in KOH, containing CeCl3, PrCl3 or TbCl3 (0.1-0.01 mol dm-3) gave stable solutions of yellow Pr4+ (Amax = 283 nm), dark reddish-brown Tb4+ (Amax = 365 nm), and of... 

Many assayers use slaked lima alone others add with the lime small portions of the alkaline carbonates, or borax, which often facilitate the fusion, especially with such ores as contain much silica and alumina, and are, consequently, very refractory. 

Braude states, that the salts of magnesia are mostly soluble in water, and bitter they are all soluble in hydrochloric acid their aqueous solutions are precipitated by potassa and soda, the precipitate, being soluble In hydrochloric, nitric, and sulphuric acids, and in hydroohlorate, nitrate, and sulphate of ammonia. Ammonia only throws down part of the magnesia, and forms a double salt, and carbonates of potassa and soda only throw down part of the magnesia, except the solution be hentad, when pearly the whole is precipitated. Chloride of ammonium redissolves tiro deposit, and when previously added to the magnesian solution, no precipitate ensues on adding the alkaline carbonates, unless the liquor be warmed The bicarbonates of von. ir. 

The proportions cf soda ash aud lime employed vary according to the degree of strength of the-eodaj similarly with regard to the potassa salt It is, however, always an advantage to have an excess of lime over the alkaline carbonate, as in tho contrary case any uudecomposed carbonate is totally lost.. 

If an alkaline carbonate be employed, all the earthy salts—calcareous and magnesian sulphates, chlorides, bicarbonates, and carbonates of the earths—are precipitated, while alkaline sulphates, chlorides, aod bioar-bonates which do not communicate hardness to water, aro left in solution. If carbonate of soda be employed, its reaction on sulphate of lime and chloride of magne slum will be as follows—... 

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