The Riddle of Atmospheric Oxygen: Photosynthesis or Photolysis?

The stoichiometry of the photosynthetic reaction requires that the quantities of the end products (organic biomaterial and free oxygen) be equal. However, the correct balance of the amounts of oxygen and organic matter that could have been produced by green plants on the land and in the ocean since the emergence of unique oxygenic photosynthetic systems (no more than 2.7 billion years ago) is virtually impossible, since the vast majority of oxygen was lost in oxidizing the initially reducing matter of the planet, and the bulk of organic carbon is scattered in sedimentary rocks. In recent decades, convincing information has been obtained in favor of the large-scale photolysis of water molecules in the upper atmosphere with the scattering of light hydrogen into space and the retention of heavier oxygen by gravity. This process has been operating continuously since the formation of the Earth. It is accompanied by huge losses of water and the oxidation of salts of ferrous iron and sulfide sulfur in the oceans and methane in the atmosphere. The main stages of the evolution of the atmosphere and surface layers of the Earth’s crust are analyzed for the first time in this work by considering the parallel processes of photosynthesis and photolysis. Large-scale photolysis of water also provides consistent explanations for the main stages in the evolution of the nearest planets of our Solar System.

Ore treatment hydrogen peroxide during heap leaching of gold

Over the past century, many problems have been focused on the problems of low leaching rate of gold and methods have been developed to intensify the leaching of gold. Among these methods, the use of hydrogen peroxide to accelerate the leaching of gold is known. In order to intensify the leaching process, the indicators of cyanide leaching of gold from ore using hydrogen peroxide were studied. This article presents the results of assay-gravimetric, chemical, and mineralogical analyses of gold-bearing ore from the Sari Gunay Deposit (Iran). The content of sulfide sulfur ore belongs to the category of low-sulphide, by oxidation of sulphur (50.70%) to the category of oxidized ores. Thermodynamic analysis of possible reactions of ore components with hydrogen peroxide is carried out. Laboratory studies on cyanide leaching of gold have shown that the maximum recovery of gold is 52.92% at a concentration of hydrogen peroxide of 0.5%, the recovery of gold without ore treatment is 52.03%. The results of laboratory and column tests with and without treatment with hydrogen peroxide (H2O2–0.5%) were compared. Treatment of gold-bearing ore with hydrogen peroxide during heap leaching of gold increases gold recovery by 1.2% and amounts to 55.89%, without treatment - 54.69%. This increases the consumption of sodium cyanide by 0.04 kg/t.

Effective Desulfurization and Alumina Digestion of High-Sulfur Bauxite by New Roasting Process with Conveying Bed

A new roasting process with a conveying bed was constructed and used to remove sulfur of high-sulfur bauxite. Roasting temperature, phase transformation, microcrystal, specific surface area of high-sulfur bauxite, and the mechanism of the reaction during the roasting process were analyzed. The digestion properties of roasted bauxite were also investigated. The results showed that the sulfur in high-sulfur bauxite can be efficiently removed by roasting in the conveying bed at 520–720 °C for 2 s. Major reactions of high-sulfur bauxite during roasting were the dehydration of minerals, desulfurization of pyrite, sulfation of SO2, and decomposition of sulfate. The rate of mineral dehydration reaction was significantly slower than that of the desulfurization reaction. The specific surface area of roasted ore greatly increased, and the microcrystal of Al-O mineral was refined, which was conducive to Al2O3 digestion. The mass fraction of sulfide sulfur in high-sulfur bauxite was reduced from 1.20% to 0.01%, and the relative digestibility of alumina reached more than 99% when roasting at 600 °C for 2 s. This paper provides revelations and instructions for the process development and application of high-sulfur bauxite.

Study of the reactions of interaction of alkylxanthogenates with chlorine derivatives of glycerin and study of lubricating properties of synthesized compounds

The reactions of 1-chloropropanediol and 1-chloro-3-alkylcarboxymethyl-propanol-2 with alkylxanthogenates have been studied; mixtures of acyclic, cyclic xanthates and tritiocarbonates are formed. The dependence of the direction of the reaction and, accordingly, the yields of the synthesized compounds on the ratio of reagents and conditions of the experiments was revealed. The evidence that both acyclic and cyclic compounds are formed in these reactions are spectral (IR) and physicochemical (n_D^20, d_4^20, MRD, elemental composition). The obtained compounds were investigated as extreme pressure additives to lubricating oils, their effectiveness as extreme pressure additives was revealed. The high extreme pressure properties of the synthesized compounds are explained by the fact that their molecules contain polar thiocarbonyl (C=S), 1 sulfide (CS) sulfur in xanthates and 2 sulfide sulfur in tritiocarbonates, which are easily adsorbed on the metal surface, forming at high temperatures, protective layer consisting of metal sulfides. Due to the fact that all the obtained compounds are high-sulfur, they do not have antiwear properties, that is, they cause corrosive wear, in order to improve the corrosive properties of oils, the authors have compiled compositions using the antiwear and antioxidant additives DF-11.

BEHAVIOUR OF SULFUR, ARSENIC AND ORGANIC CARBON IN A GRAVITY CONCENTRATION OF GOLD FROM REFRACTORY ORE

The results of assay-gravimetric, chemical, mineralogical analyzes of gold ore are presented. According to the content of sulfide sulfur and the degree of oxidation of sulfur gold-bearing ore is assigned to the poor sulfide type of ore in the primary zone. Gold ore refers to refractory carbonaceous arsenic-containing sulfide ores. The gravity concentration of ore was assessed using a laboratory 3-inch Knelson KC-MD3 centrifugal concentrator. According to the results of the GRG test, the total gold extraction was 39.58% with the total concentrate yield of 3.96%. The extraction of gold in the first stage is lower than in the subsequent stages. This indicates the absence of large gold in the ore. The behavior of sulfur and arsenic during gravity concentration is similar to the behavior of gold. These data confirm that the main amount of gold is associated with arsenopyrite (arsenic pyrite) and pyrite. The behavior of organic carbon during gravity is significantly different. Only 3.39% of organic carbon passes into the gravity concentrate from ore, which reduces the persistence of the concentrate. Most of the organic carbon (96.61%) remains in the tails of gravity. The content of components in the total gravity concentrate was: Au 21.63 g/t, S 6.40%, As 0.82%, C(organic) 0.58%. The extraction of the components in the total concentrate is as follows, %: Au 39.58; S 34.52; As 27.27; C(organic) 3.39.