Sulfides base metal

FIGURE 11.3 Summary of Chevron study on white oil hydrotreatment using noble metal and sulfided base metal catalysts reactor outlet temperatures versus product quality. Source M. L. Diringer and C. R. Hare, Two-Stage Hydrotreatment for White Oil Manufacture, U.S. Patent 3,340,181. With permission. 

The BASF15 and IFP12 processes are reported to use sulfided NiO/MoO catalysts, and catalysts of this general sulfided base metal type can be expected to be employed by all licensors. While noble metal or nickel catalysts result in low reactor temperatures, their use is unlikely in this application. Sulfur levels in the feeds make for short catalyst life unless they are from dewaxing a hydro-crackate. 

Soils found near sulfidic base metal deposits under active decay may have three principal kinds of mercury compounds (1) organically complexed and adsorbed on clay, as in aerated soils, (2) inorganic salts. 

Sulfidic base metal a metal chemically more active than gold, silver, and platinum metals. Commonly restricted to the ore metals, such as... 

Deposits. Selenium forms natural compounds with 16 other elements. It is a main constituent of 39 mineral species and a minor component of 37 others, chiefly sulfides. The minerals are finely disseminated and do not form a selenium ore. Because there are no deposits that can be worked for selenium recovery alone, there are no mine reserves. Nevertheless, the 1995 world reserves, chiefly in nonferrous metals sulfide deposits, are ca 70,000 metric tons and total resources are ca 130,000 t (24). The principal resources of the world are in the base metal sulfide deposits that are mined primarily for copper, zinc, nickel, and silver, and to a lesser extent, lead and mercury, where selenium recovery is secondary. 

Like selenium, tellurium minerals, although widely disseminated, do not form ore bodies. Hence, there are no deposits that can be mined for tellurium alone, and there are no formally stated reserves. Large resources however, are present in the base-metal sulfide deposits mined for copper, nickel, gold, silver, and lead, where the recovery of tellurium, like that of selenium, is incidental. 

Antimony tris(isooctylthioglycolate) has found use in pipe formulations at low levels. Its disadvantage is that it cross-stains with sulfide-based tin stabilizers (122). Barium—zinc stabilizers have found use in plasticized compounds, replacing barium—cadmium stabilizers. These are used in mol dings, profiles, and wire coatings. Cadmium use has decreased because of environmental concerns surrounding certain heavy metals. 

Montana. These deposits consist of stibnite and other sulfide minerals containing base metals and silver or gold. Ores of the complex deposits are mined primarily for lead, copper, 2inc, or precious metals antimony is a by-product of the treatment of these ores. 

In the second phase, performed at a maximum temperature of about 370°C, the sulfur and a portion of the coke are removed by combustion. The rate and exothermicity are controlled by limiting the flow of combustion gas through the catalyst. Spent base metal catalysts may have sulfur levels of from 6 to 12 wt % in the form of metal sulfides. A high degree of sulfur removal must be achieved in these first two regeneration steps to avoid the formation of sulfate on the support during the final combustion step. Such a formation causes a loss of catalyst activity. 

The two types of hot eorrosion eause different types of attaek. High-temperature eorrosion features intergranular attaek, sulfide partieles and a denuded zone of base metal. Metal oxidation oeeurs when oxygen atoms eombine with metal atoms to form oxide seales. The higher the temperature, the more rapidly this proeess takes plaee, ereating the potential for failure of the eomponent if too mueh of the substrate material is eon-sumed in the formation of these oxides. 

Epithermal base-metal vein-type deposits are characterized by the abundant occurrence of sulfides (chalcopyrite, pyrite, sphalerite, galena), and a scarcity of Au-... 

The /02 of ore fluids responsible for the epithermal base-metal veins might have been in the predominance field of reduced sulfur species because (1) pyrrhotite is occasionally found in these deposits, (2) selenium content of argentite is very low and (3) H2S is dominant in the present-day epithermal base-metal fluids. Implication of selenium content of sulfides will be considered later. Barite is sometimes found in the late-stage of mineralization. Thus, it is likely that /oj of barite stage lies in the predominance field of oxidized sulfur species. 

The concentrations of base-metals (Cu, Fe, Pb, and Zn) in hydrothermal solution in equilibrium with sulfides (chalcopyrite, pyrite, galena and sphalerite) depend on several variables such as pH, ntQx- concentration, temperature, /WH2S, and fo2- The relation between the concentrations and these variables can be derived based on the chemical equilibrium for the following reactions. 

Figure 1.107 shows the frequency of 8 C of carbonates from epithermal Au-Ag vein-type deposits and that from base-metal vein-type deposits. The carbonates are divided into two types type A and type B. Type A is characterized by (1) abundant occurrence in each deposit (2) coexistence with sulfide minerals and (3) large grain size. Main carbonate minerals are rhodochrosite and Mn calcite, whereas calcite is the main carbonate mineral for type B. Mn-carbonates of type A occur in Pb-Zn-Mn vein-type deposits. Type B is characterized by (1) poor amounts in each deposit (2) coexistence... 

S values of epithermal base metal deposits are higher than those of the epithermal Au-Ag deposits and range mostly from - -3%c to -f-7%o (Fig. 1.111). Although most of 8 " S values for base-metal deposits lie in this range, 8- " S of composite sample of sulfides from the Motokura Cu-Pb-Zn deposits, Ohmori Cu-Ag deposits, Hosokura Pb-Zn deposits, Sasayama Cu-Pb-Zn deposits and Imai-lshizaki Cu-Pb-Zn deposits are low, that is, -1-0.1, -1-1.8, -1-2.2, —0.9 and —2.1%o, respectively (Shikazono, 1987b Shikazono and Shimizu, 1993). 

Figure 1.109. Sulfur isotopic compositions of Neogene Au-Ag vein-type and disseminated-type deposits. Sulfur isotopic compositions on the samples from the Yatani deposits (Sample No. YT26 from Zn-Pb vein S S = -)-3.3%o), and HS72050305-YT1, YT24 and NS-3 from Au-Ag vein (average S S = +3.3%c)) by Shikazono and Shimazaki (1985) are also plotted. Base-metal rich implies the sample containing abundant sulfide minerals but no Ag-Au minerals from base-metal rich deposits and also from Ginguro-type deposits (Shikazono, 1987b).

Figure 1.111. Sulfur isotopic values for sulfides from base-metal vein-type deposits (Shikazono, 1987b).

Origin of sulfide sulfur of epithermal base-metal veins is thought to be same as that of Kuroko deposits because average 8 S value of base-metal vein-type deposits is - -4.7%o which is identical to that of Kuroko deposits (- -4.6%o) (Shikazono, 1987b). Namely, sulfide sulfur of base-metal veins came from igneous rocks, sulfate of trapped seawater in marine sedimentary rocks, calcium sulfate (anhydrite, gypsum) and pyrite. 8 S of sulfide sulfur of epithermal base-metal vein-type deposits can be explained by the interaction of seawater (or evolved seawater) with volcanic rocks. 

Possibility (1) was proposed by Shikazono (1987b) who considered that the lower values of sulfide sulfur than base-metal vein-type deposits and Kuroko deposits can be explained by the leaching of sulfide sulfur from volcanic rocks with lower values (0%o to -t-5%o) (Uyeda and Sakai, 1984). 

---