Bismuth precipitated

The final ceU product contains 250—300 g/L H2SO in the last stages of electrolyte purification, and antimony and bismuth precipitate, resulting in heavily contaminated cathodes that are recycled through the smelter. Arsenic and hydrogen evolved at the cathodes at these later stages react to form arsine, and hoods must be provided to collect the toxic gas. 

In order to estimate% conversion, precipitate was filtered, washed with C2H5OH and dried at 60°C before weighed. Different amounts of bismuth precipitated in solutions of bismuth nitrate, Bi(N03)3, of the concentration 0.071-0.111 M between the pH range 0.9-0.5 respectively, were estimated gravimetrically and given in the Table 9.16. These Bi3+ solutions were sonicated above autohy-drolytic concentration and pH. Hydrolysis began in the form of precipitate due to the formation of BiO(N03). At lower concentration [0.071 M of Bi(N03)3], precipitation started immediately upon sonication, whereas, the time for the appearance of turbidity increased as the concentration increased to 0.111 M. This was perhaps because of the availability of more water molecules for interaction with Bi3+ ions in dilute solutions. Ultrasonically induced hydrolysis was therefore... 

Sixty-five milliliters of concentrated nitric acid is then added and the solution boiled until oxides of nitrogen have been expelled. Basic nitrates of antimony and bismuth precipitate at this point if these substances are present as impurities. These are removed by filtering through asbestos, after which the clear liquor is evaporated gently on a water bath under a hood in an open 600-ml. beaker. Basic tellurium nitrate is deposited. The evaporation is continued until the solution volume has been reduced to 100 ml. The solution is then cooled. The crystalline deposit is filtered, washed with water on a suction filter, and air-dried. 

In June 1898 a radioactive element in the bismuth precipitate was characterised and named polonium from the native country of one of us (Poland). In December 1898 a new element, named radium in the barium precipitate was announced. The still impure radium preparation had an activity a million times that of uranium. E. Demar9ay showed that radium had a characteristic spark spectrum. ... 

In their hunt for new elements, Marie and Pierre Curie treated a batch of material with strong hydrochloric acid. Both the solution and the insoluble residue were radioactive. From the hydrochloric add solution, sulfides were precipitated with hydrogen sulfide. The radioactivity followed bismuth. Andre Debieme introduced a modified technique. An iron foil was placed in the acid solution. Metals nobler than iron, thus copper, lead and bismuth, precipitated, at least partially. The radioactivity followed this metallic fraction. 

Iron (ill), cobalt, copper, zinc, cadmium, mercury, emd bismuth precipitate. 

Solutions of many antimony and bismuth salts hydrolyse when diluted the cationic species then present will usually form a precipitate with any anion present. Addition of the appropriate acid suppresses the hydrolysis, reverses the reaction and the precipitate dissolves. This reaction indicates the presence of a bismuth or an antimony salt. 

When hydrogen sulphide is bubbled into an acidic solution of an antimony or a bismuth salt an orange precipitate, SbjSs, or a brown precipitate, BijS, is obtained. Bismuth(III) sulphide, unlike antimony(IIl) sulphide, is insoluble in lithium hydroxide. 

Direct Titrations. The most convenient and simplest manner is the measured addition of a standard chelon solution to the sample solution (brought to the proper conditions of pH, buffer, etc.) until the metal ion is stoichiometrically chelated. Auxiliary complexing agents such as citrate, tartrate, or triethanolamine are added, if necessary, to prevent the precipitation of metal hydroxides or basic salts at the optimum pH for titration. Eor example, tartrate is added in the direct titration of lead. If a pH range of 9 to 10 is suitable, a buffer of ammonia and ammonium chloride is often added in relatively concentrated form, both to adjust the pH and to supply ammonia as an auxiliary complexing agent for those metal ions which form ammine complexes. A few metals, notably iron(III), bismuth, and thorium, are titrated in acid solution. 

Metals less noble than copper, such as iron, nickel, and lead, dissolve from the anode. The lead precipitates as lead sulfate in the slimes. Other impurities such as arsenic, antimony, and bismuth remain partiy as insoluble compounds in the slimes and partiy as soluble complexes in the electrolyte. Precious metals, such as gold and silver, remain as metals in the anode slimes. The bulk of the slimes consist of particles of copper falling from the anode, and insoluble sulfides, selenides, or teUurides. These slimes are processed further for the recovery of the various constituents. Metals less noble than copper do not deposit but accumulate in solution. This requires periodic purification of the electrolyte to remove nickel sulfate, arsenic, and other impurities. 

Bismuth vanadate can be produced by chemical precipitation, as weU as by high temperature calciaation methods. In the wet process, the acidic solution of bismuth nitrate, Bi(N02)3, is mixed with the alkaline solution of sodium vanadate, Na VO. The gel formed is filtered off on a filter, pressed, washed, and converted to a crystalline form by calciaation at low temperatures of 200—500°C for 1 h (37,38). 

The first successflil production method for the separation of Pu from U and its fission products was the bismuth phosphate process, based on the carrying of Pu by a precipitate of BiPO (126). That process has been superseded by Hquid-Hquid extraction (qv) and ion exchange (qv). In the Hquid-Hquid... 

The gases from the several furnaces treating the slimes carry bismuth, silver, gold, and other values as particulates, which are recovered via Cottrell precipitators, baghouses, or scmbbers. 

Recovery of Bismuth from Tin Concentrates. Bismuth is leached from roasted tin concentrates and other bismuth-beating materials by means of hydrochloric acid. The acid leach Hquor is clarified by settling or filtration, and the bismuth is precipitated as bismuth oxychloride [7787-59-9] BiOCl, when the Hquors are diluted usiag large volumes of water. The impure bismuth oxychloride is usually redissolved ia hydrochloric acid and reprecipitated by diluting several times. It is then dried, mixed with soda ash and carbon, and reduced to metal. The wet bismuth oxychloride may also be reduced to metal by means of iron or 2iac ia the presence of hydrochloric acid. The metallic bismuth produced by the oxychloride method requites additional refining. 

Complexes of BiF are almost unknown, but crystaUi2ation from a hot solution of ammonium duoride that has been saturated with freshly precipitated bismuth trioxide yields crystals of ammonium tetraduorobismuthate(III) [13600-76-5] NH BiF. This complex is readily decomposed by water. 

Bismuth pentafluoride is an active fluorinating agent. It reacts explosively with water to form ozone, oxygen difluoride, and a voluminous chocolate-brown precipitate, possibly a hydrated bismuth(V) oxyfluoride. A similar brown precipitate is observed when the white soHd compound bismuth oxytrifluoride [66172-91 -6] BiOF, is hydrolyzed. Upon standing, the chocolate-brown precipitate slowly undergoes reduction to yield a white bismuth(Ill) compound. At room temperature BiF reacts vigorously with iodine or sulfur above 50°C it converts paraffin oil to fluorocarbons at 150°C it fluorinates uranium tetrafluoride to uranium pentafluoride and at 180°C it converts Br2 to bromine trifluoride, BrF, and bromine pentafluoride, BrF, and chlorine to chlorine fluoride, GIF. It apparently does not react with dry oxygen. 

Bismuth trioxide may be prepared by the following methods (/) the oxidation of bismuth metal by oxygen at temperatures between 750 and 800°C (2) the thermal decomposition of compounds such as the basic carbonate, the carbonate, or the nitrate (700—800°C) (J) precipitation of hydrated bismuth trioxide upon addition of an alkah metal hydroxide to a solution of a bismuth salt and removal of the water by ignition. The gelatinous precipitate initially formed becomes crystalline on standing it has been represented by the formula Bi(OH)2 and called bismuth hydroxide [10361 -43-0]. However, no definite compound has been isolated. 

Bismuth subcarbonate [5892-10 ] (basic bismuth carbonate) is a white or pale yellow powder that is prepared by interaction of bismuth nitrate and a water-soluble carbonate. The exact composition of this dmg depends on the conditions of precipitation it corresponds approximately to the formula (Bi0)2C02. It has been widely used as an antacid (183). 

Chlorination of bismuth or mercuric oxides results in precipitation of relatively insoluble basic chlorides, ie, BiOCl and HgO HgCl2. However, the reaction with is slow and does not produce high concentrations of HOCl (121). With HgO, the HOCl solutions may contain significant amounts of... 

The precipitated copper from this reaction is an important constituent of the slime that collects at the bottom of the electrolytic cells. The accumulation of copper as well as of impurities such as nickel, arsenic, antimony, and bismuth is controlled by periodic bleed-off and treatment in the electrolyte purification section. 

By-Product Recovery. The anode slime contains gold, silver, platinum, palladium, selenium, and teUurium. The sulfur, selenium, and teUurium in the slimes combine with copper and sUver to give precipitates (30). Some arsenic, antimony, and bismuth can also enter the slime, depending on the concentrations in the electrolyte. Other elements that may precipitate in the electrolytic ceUs are lead and tin, which form lead sulfate and Sn(0H)2S04. 

Among arsenic, bismuth, lead, antimony, and sulfur in the concentration range of 5—26 ppm, bismuth had the greatest unit effect (59). A decrease in the annealing temperature prior to cold deformation led to a decrease in the measured unit effectiveness, indicating that at low temperature bismuth is not in sohd solution. Lead lowered the recrystaUization temperature, provided that the samples were aimealed at 700°C or lower. A precipitation reaction between lead and sulfur was proposed (60). 

Perhaps the most reactive compound of the group is BiFs- It reacts extremely vigorously with H2O to form O3, OF2 and a voluminous brown precipitate which is probably a hydrated bismuth(V) oxide fluoride. At room temperature BiFs reacts vigorously with iodine or sulfur above 50° it converts paraffin oil to fluorocarbons at 150° it fluorinates UF4 to UF and at 180° it converts Brs to BrFs and BrFs, and CI2 to CIF. 

The following are suitable anions for urea precipitations of some metals sulphate for gallium, tin, and titanium formate for iron, thorium, and bismuth succinate for aluminium and zirconium. 

Metaphosphoric acid may also be used it hydrolyses in warm acid solution forming phosphoric(V) acid. Thus bismuth may be precipitated as bismuth phosphate in a dense, crystalline form. 

H. 8-Hydroxyquinaldine (XI). The reactions of 8-hydroxyquinaldine are, in general, similar to 8-hydroxyquinoline described under (C) above, but unlike the latter it does not produce an insoluble complex with aluminium. In acetic acid-acetate solution precipitates are formed with bismuth, cadmium, copper, iron(II) and iron(III), chromium, manganese, nickel, silver, zinc, titanium (Ti02 + ), molybdate, tungstate, and vanadate. The same ions are precipitated in ammoniacal solution with the exception of molybdate, tungstate, and vanadate, but with the addition of lead, calcium, strontium, and magnesium aluminium is not precipitated, but tartrate must be added to prevent the separation of aluminium hydroxide. 

Procedure. The cold bismuth nitrate solution, containing 0.1-0.15 g of Bi (Note 1), must be slightly acid with nitric acid (Note 2), and occupy a volume of about 20 mL. Add finely powdered solid potassium iodide, slowly and with stirring, until the supernatant liquid above the black precipitate of bismuth tri-iodide is just coloured yellow (due to K[BiI4]). Dilute to 200mL with boiling water, and boil for a few minutes. The black tri-iodide is converted into... 

Cations forming insoluble chromates, such as those of silver, barium, mercury (I), mercury(II), and bismuth, do not interfere because the acidity is sufficiently high to prevent their precipitation. Bromide ion from the generation may be expected to form insoluble silver bromide, and so it is preferable to separate silver prior to the precipitation. Ammonium salts interfere, owing to competitive oxidation by bromate, and should be removed by treatment with sodium hydroxide. 

Determination of copper as copper(I) thiocyanate Discussion. This is an excellent method, since most thiocyanates of other metals are soluble. Separation may thus be effected from bismuth, cadmium, arsenic, antimony, tin, iron, nickel, cobalt, manganese, and zinc. The addition of 2-3 g of tartaric acid is desirable for the prevention of hydrolysis when bismuth, antimony, or tin is present. Excessive amounts of ammonium salts or of the thiocyanate precipitant should be absent, as should also oxidising agents the solution should only be slightly acidic, since the solubility of the precipitate increases with decreasing pH. Lead, mercury, the precious metals, selenium, and tellurium interfere and contaminate the precipitate. 

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