Oxidation of minerals

A combined addition of a chain-breaking inhibitor and a hydroperoxide-breaking substance is widely used to induce a more efficient inhibition of oxidative processes in polyalkenes, rubbers, lubricants, and other materials [3 8]. Kennerly and Patterson [12] were the first to study the combined action of a mixture, phenol (aromatic amine) + zinc dithiophosphate, on the oxidation of mineral oil. Various phenols and aromatic amines can well serve as peroxyl radical scavengers (see Chapter 15), while arylphosphites, thiopropionic ethers, dialkylthio-propionates, zinc and nickel thiophosphates, and other compounds are used to break down hydroperoxide (see Chapter 17). Efficient inhibitory blends are usually prepared empirically, by choosing such blend compositions that induce maximal inhibitory periods [13],... 

Abstract The flotation mechanism is discussed in the terms of corrosive electrochemistry in this chapter. In corrosion the disolution of minerals is called self-corrosion. And the reaction between reagents and minerals is treated as inhibition of corrosion. The stronger the ability of inhibiting the corrosion of minerals, the stronger the reagents react with minerals. The two major tools implied in the research of electrochemical corrosion are polarization curves and EIS (electrochemistry impedance spectrum). With these tools, pyrite, galena and sphalerite are discussed under different conditions respectively, including interactions between collector with them and the difference of oxidation of minerals in NaOH solution and in lime. And the results obtained from this research are in accordance with those from other conventional research. With this research some new information can be obtained while it is impossible for other methods. 

Oxidation of mineral oils By using data in Figure 2.7, discuss the oxidation tendency of mineral oils as a function of base oil, degree of refining and the addition of metals and additives. 

I. Marsden and I. House, in The Chemistry of Gold Extraction, Ellis Horwood, Chichester, 1992 S. Mann, Nature, 1992,357, 358 H. CoUey, Chem. Brit., 1992,720 J. Barrett, M.N. Hughes, G.I. Karavaiko and P.A. Spencer, in Metal Extraction by Bacterial Oxidation of Minerals, Ellis Horwood, Chichester, 1992. 

J. Barrett, M. N. Hughes, G. I. Karavaiko, and P. A. Spencer, Metal Extraction by Bacterial Oxidation of Minerals , EUis Horwood, Chichester, 1993. 

Inorganic pH controls include hydrolysis and oxidation of minerals and are sensitive to atmospheric partial pressures of both CO2 and oxygen. Higher partial pressure of CO2 results in increased acidity, which can be neutralized by hydrolysis. Oxidation produces acidity, whereas hydrolysis reactions increase pH or alkalinity and release silicic acid. 

The existence of these chemical pathways for the oxidation of minerals during bacterial leaching does not exclude a direct role for bacteria. Both pathways may occur simultaneously, the relative importance of each depending upon the rate constants for the reactions and the concentration of Fe(III) present in solution. Experiments carried out on synthetic iron-free cobalt and nickel sulfides, using carefully washed cells of T. ferrooxidans to ensure the absence of Fe(III), showed consumption of oxygen and the solubilization of the metal as sulfate. Solubilization rates were appreciably increased on the addition of Fe(III). These results present support for the presence of both direct and indirect pathways (116). Recently, attempts have been made to compare the rates of these pathways for the oxidation of pyrite by T. ferrooxidans (74). 

Mgssbauer Spectroscopy. MCTssbauer spectroscopy has been found to be a valuable tool in identifying the multiple iron species found in coal and coal-related materials (62,63). A combination of Mffssbauer spectroscopy and FT-IR has been used to study the low temperature oxidation of minerals in bituminous coal (6 ). 

Fio. 9-7. Type of apparatus used for oxidation of mineral oils by James process. 

Environment and Life, RSC Publishing, p. i60 As this cytoplasmic (in cell) organic chemistry was reductive of necessity, because the ingredients were made of the oxides of carbon, it was inevitable that oxidizing compounds, which became oxygen, would be released. There followed in the environment an unavoidable and predictable sequence of the oxidation of minerals and non-metal elements in solution, limited by diffusion but generally following sequentially equilibrium constants, redox potentials. ... 

---