Antimony metallic

The Bunker Hill Co. (15) and ASARCO, Inc. (16) have developed processes for the leaching and electrowinning of antimony from tetrahedrite ores. As of 1991, only Sunshine Mining Co. was electrowinning antimony metal. 

Total smelter output in the United States has been growing steadily since 1982 because of the growth in antimony oxide production. Primary antimony metal output has decreased since the 1970s because of the falling demand for antimony metal, and the availabihty of low cost metal from China. 

Prices. The price of antimony metal has declined steadily since 1984. The principal reason for the fall in antimony prices is the oversupply of material, especially from Chinese sources, in relation to demand, which has been stable or decreasing during the 1980s. Antimony prices have fallen to such an extent that some producers of antimony products now find it more economical to use antimony metal as feed material in place of antimony ore and concentrates. 

Sb. Commercial antimony metal, in aqueous 1 M HC1 or DC1 solution, reacts with allyl bromide and aldehydes to give the corresponding homoallylic alcohols in good yield. The reaction proceeds through the formation of allylstibine intermediates.179 The same allylation can be... 

Mechanism [4] was based on studies involving the direct reaction of antimony metal with DBDPO in the absence of a hydrogen source. The data from these experiments clearly show that if the oxide is reduced to the metal, direct interaction with DBDPO would occur, and that this is a specific and highly exothermic reaction. However, no direct evidence for the presence of metallic antimony in mixtures containing antimony oxide, a polymer substrate and an organohalogen compound was obtained. 

All of the organohalogen compounds studied were commercial products obtained from various manufacturers and used as received. Only the DBDPO was purified further by recrystallization for some of the chromatography and thermal analysis experiments. Samples of antimony trioxide and antimony pentoxide were also obtained from commercial sources. The ultrapure antimony trioxide, bismuth trioxide, bismuth metal, antimony metal, dibenzofuran and diphenyl ether were all obtained from Aldrich Chemicals. The poly(propylene) (PP) resin was 0.7 mfi, food grade from Novamont and the poly(ethylene) was unstabilized, high molecular weight, HDPE from American Hoechst. 

Previous thermal analysis studies had indicated that while Sb203 did not react directly with DBDPO, there was some evidence that the reaction of a polymer substrate with the Sb203 generated a species which was very reactive (23), and that this product was antimony metal (Sb°). Therefore, simple mixtures of DBDPO with powdered antimony, bismuth and zinc metals (mole ratio of bromine to metal of 3 1) were pyrolyzed and the extent of reaction determined by CGC. 

Experiments with antimony metal and DBDPO clearly demonstrated for the first time that antimony volatilization was possible in the complete absence of any source of hydrogen at polymer pyrolysis temperatures. 

Preparation. Antimony metal is obtained by pyrometallurgical methods. The sulphide is converted into the oxide, which can be directly reduced by carbon. 

Department of Labor Antimony metal antimony trioxide and antimony sulfide response to the interagency testing committee. Fed Reg 48 717-724, 1983... 

Alternatively, heating antimony metal or antimony trioxide with sulfur forms antimony trisullide ... 

Antigrisou (Explosifs) A466-R Antimony, Metal A467 R Antimony, Analytical Procedures A469 to A470... 

Several studies have been made of the effect of added metal ions on the pinacol/alcohol ratio. Addition of antimony(m) chloride in catalytic amounts changes the product of the electrochemical reduction of acetophenone in acidic alcohol at a lead electrode from the pinacol in the absence of added metal salt to the secondary alcohol in its presence53. Antimony metal was suspected to be an intermediate in the reduction. Conversely, addition of Sm(in) chloride to DMF solutions of aromatic aldehydes and ketones54 and manganese(II) chloride to DMF solutions of hindered aromatic ketones55 results in selective formation of pinacols in excellent yields. When considering these results one should keep in mind the fact that aromatic ketones tend to form pinacols in DMF even in the absence of added metal ions1,29,45. 

Antimony—metal complexes, characteristics, 2, 34 Anti-proliferation drugs, for parasites, 12, 458 159 Anti-tumor effects, Ti(IV) complexes, 4, 662 (—)-Antofine, via ring-closing diene metathesis, 11, 222 (t-)-Aphanomol 1, via [5+2]-cycloadditions, 10, 613-614 Apical ligands, iron complexes with, 6, 313 Aqua ligands... 

Phillips Petroleum Company discovered and developed the antimony metals passivation process in the early 1970 s, and successfully applied the process at its Borger, Texas heavy oil cracker (HOC) in 1976 (2). For catalytic cracking units with... 

Specific commercial performance benefits obtained with the antimony metals passivation process and methods used for evaluating potential benefits are discussed. Options for maximizing benefits are also presented. 

Antimony metals passivation technology has been utilized in a variety of FCC unit designs, with a wide range of FCC catalysts (14, 9). In addition, antimony metals passivation has been commercially proven over a broad range of catalyst metals concentrations. As the catalyst metals level increases, the passivation performance improves. A study of over 25 commercial trials revealed that the average hydrogen reduction improved from 35% to 45% as the metals levels increased from less than 6000 ppm (4Ni+V) to over 9000 ppm (4Ni+V), Figure 2. 

Case Studies. As shown in Figure 2, metals passivation is utilized effectively with 4Ni+V concentrations less than 6000 ppm. Specific benefits of antimony metals passivation for two refinery FCC units operating at less than 6000 ppm 4Ni+V are discussed below. 

Table II. Antimony Metals Passivation Effects on Charge Rate...

For those redox couples that involve a metal ion plus the metal, the logical electrode system is the metal itself. In other words, if the measured quantity is to be cupric ion [copper(II)], a practical indicator electrode is a piece of copper metal. All second-class electrodes involve an active metal in combination with an insoluble compound or salt. Thus, the silver/silver chloride electrode actually is a silver/silver ion electrode system that incorporates the means to control the silver ion concentration through the chloride ion concentration [Eq. (2.14)]. A related form of this is the antimony electrode, which involves antimony and its oxide (an adherent film on the surface of the antimony-metal electrode) such that the activity of antimony ion is controlled by... 

For adverse conditions (in terms of either temperature or vibration) the antimony electrode has proved useful, particularly for industrial processes with extreme environmental problems. The electrode is not particularly reliable for precise measurements, but its simple form (consisting of antimony metal embedded in an insulating material) allows pH measurements under such adverse conditions. The principle of the electrode is based on a half-reaction whereby the metal and its metal oxide are both insoluble and the electrode s response is dependent on hydronium ion activity ... 

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