Beryllium concentration

A beryllium concentrate is produced from the leach solution by the counter-current solvent extraction process (10). Kerosene [8008-20-6] containing di(2-ethylhexyl)phosphate [298-07-7] is the water-immiscible beryllium extractant. The slow extraction of beryllium at room temperature is accelerated by warming. The raffinate from the solvent extraction contains most of the aluminum and all of the magnesium contained in the leach solution. 

Assay of beryllium metal and beryllium compounds is usually accomplished by titration. The sample is dissolved in sulfuric acid. Solution pH is adjusted to 8.5 using sodium hydroxide. The beryllium hydroxide precipitate is redissolved by addition of excess sodium fluoride. Liberated hydroxide is titrated with sulfuric acid. The beryllium content of the sample is calculated from the titration volume. Standards containing known beryllium concentrations must be analyzed along with the samples, as complexation of beryllium by fluoride is not quantitative. Titration rate and hold times are critical therefore use of an automatic titrator is recommended. Other fluoride-complexing elements such as aluminum, silicon, zirconium, hafnium, uranium, thorium, and rare earth elements must be absent, or must be corrected for if present in small amounts. Copper—beryllium and nickel—beryllium alloys can be analyzed by titration if the beryllium is first separated from copper, nickel, and cobalt by ammonium hydroxide precipitation (15,16). 

Beryllium is not well absorbed by any route oral absorption of beryllium is less than 0.01% and probably only occurs in the acidic stomach environment. About half of inhaled beryllium is cleared in 2 weeks the remainder is cleared slowly and the residual becomes fixed in the lung (granulomata). The half-life of beryllium in rat blood is 3 h. Beryllium is distributed to all tissues. High doses generally go to the liver and then are gradually transferred to the bone. Most beryllium concentrates in the skeleton. Beryllium is excreted in the urine however, the fraction of administered dose excreted in urine is variable. 

Two methods were developed independently, in separate laboratories. The sample preparation for the two methods is essentially the same. However, because of the differences in instrumentation, separate detailed methods are required. In both methods the sample is diluted with tetra-hydrofuran, and an aliquot is injected into the atomizer. The average signals for the sample and the sample plus three standard additions are obtained. After appropriate blank corrections have been made, the beryllium concentration is obtained by graphical or calculation techniques. 

Calculate the beryllium concentration after each standard addition as follows ... 

Extrapolate the line through the series of points until it intersects the ng Be/g axis. The ng Be/g at the point of intersection is the beryllium concentration in nanograms/gram in the original sample (see Chapter 3, Standard Additions). 

The aqueous beryllium sulfate is separated from the solids by counter-current decantation thickener operations. A beryllium concentrate is produced by a counter-current solvent extraction process (Maddox and Foos 1966). This concentrate is stripped of its beryllium content with aqueous ammonium carbonate. By heating to 70 °C, aluminum and iron are precipitated and then removed by filtration. Precipitation of beryllium basic carbonate occurs when the solution is heated to 95 °C. The carbonate is filtered, deionized water is added, and heating to 165 °C yields a beryllium hydroxide product which is the common input to beryllium-copper alloy, beryllium oxide ceramics, or pure beryllium metal (Table 2.1-2). 

A rapid development of certain specialized industries such as the production of computers, beryllium ceramics, nuclear power engineering, rocket techniques and other complex technologies give rise to the possibility of occupational exposure to beryllium effects. In the vicinity of works producing beryllium, its alloys or salts, and also in coal combustion (where as much as 100 g of beryllium may be present in one ton of certain types of coal), the atmosphere is polluted with this toxic element, which thus leads to the exposure of the population in these localities. The maximal permissible beryllium concentration is as low as 0.002 mg m. ... 

In the case of ICP-OES measurements scandium and/or beryllium is used as an internal standard. Differences in element concentrations in the plant digests can affect the nebuliser and/or the plasma conditions. Therefore scandium and/or beryllium will be nebulised in the plasma together with the sample. By measuring also scandium or beryllium a correction can made for all measured elements since the measured scandium or beryllium concentration should be constant. 

In comparison with other metal ions, the stability of BeOH is relatively weak at 25 °C. Polymeric species predominate in acidic solutions at beryllium concentrations above 10 molkg . Consequently, few studies of beryllium hydrolysis have been able to measure the stabUity of BeOH at this temperature. At higher temperatures, the monomers become more stable than the polymers, and, as a result, only monomers have been detected at high temperatures. 

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