Real-Time Electrical Conductivity Monitoring and Correlation with Sulfate Release and Acid Mine Drainage Potential from a Gold/Silver Paste Tailing Storage

Safe disposal of tailings as high-density thickened tailings or paste tailings can reduce the environmental risks of conventional tailings deposits, reduce water use, minimize tailings storage facility footprints, reduce the potential for acid mine drainage (AMD), and minimize risks of failure, among other advantages. In the dewatering process, the addition of flocculants is key to improving the sedimentation of the tailings and the formation of a compact paste. Despite the environmental and operational advantages of using paste tailings, it is not clear how the chemical nature of coagulants and flocculants could influence the discharge of toxic elements (salts and metals) from tailings after storage. In this study, we show the results of the real-time evaluation of the release of polluting runoffs from a paste tailings deposit. To do this, we analyzed paste tailing samples for AMD potential through static and kinetic tests and monitored the electrical conductivity and real-time pH, evaluating the correlation with the sulfate in the thickener and downstream from the tailings deposit. Tailing samples have low sulfur content (<2%) and low acid-generating potential. Moreover, there is no evidence of a significant positive correlation (Pearson’s coefficient r < 0.8) between the sulfate concentrations with the pH or EC. Thus, the chemical nature of the paste tailings prior to discharge has no direct impact on the release of sulfate-rich runoffs from the tailings after its storage. This indicates that the tailings paste at the evaluated site is chemically stable in the short term.

The origins of paraffinic oils collected from oilfields in the western Siberian Basin, Russia: implications from geochemical and physical characteristics

Four oil samples were collected from oilfields in the western Siberian Basin, and analyzed using conventional geochemical and physical methods. The results of this study were used to evaluate the oil samples, focusing on the characteristics of their source rocks, including the origin of organic matter input; redox depositional conditions and degree of thermal maturity of their probable source rock were studied. The obtained SARA results show that the examined oils are paraffinic oils owing to their high saturated hydrocarbon fraction values of greater than 70% volume. The observed API gravity values (23.55° to 32.57°) and low sulfur content of less than 0.25% wt indicate that the examined oils are sweet oils and were generated from source rock containing Type-II, with low sulfur content. The low sulfur content combined with the vanadium (V) and nickel (Ni) ratios indicates that the examined oils were scoured from a mixture of aquatic and terrestrial organic matter, depositing under generally suboxic environmental conditions. The n-alkane and isoprenoid distributions, with their ratios and parameters further suggest that the examined oil samples were generated from source rock containing a mixed organic matter input and deposited under suboxic to relatively oxic environmental conditions. Bulk compositions and distributions of n-alkane and isoprenoid indicate that the oil samples were generated from mature source rock.

Study on the Effect of Polysulfide Content on the Micromorphology and Spontaneous Combustion Characteristics of Coal

This paper aimed to study the effect of the polysulfide content on the micromorphology and spontaneous combustion characteristics of coal, in order to develop more targeted prevention and treatment strategies. To this end, this study selected the method of mixing different sulfides with very low sulfur content raw coal to prepare the coal samples to be tested. Various parameters, such as true density, porosity, micromorphology, and oxygen uptake of the different sulfur samples, were tested. The results reveal that sulfide had a certain expansion effect on the coal body and improved the pore structure of coal, and the porosity increased with the increase of the sulfur content. After adding iron (II) disulfide (FeS2) and iron (II) sulfide (FeS) powder to the original coal sample, the number of fine particles on the surface increased significantly. After increasing the oxidation temperature, the lamellar structure disintegrated, and the massive coal body was broken into several fine particles, which promoted the spontaneous combustion of coal. Polysulfide promotes the low-temperature oxygen absorption of coal and shortens the natural firing period of coal. FeS has a slightly greater effect on increasing the tendency of coal to spontaneously combust and shortening the shortest natural firing period of coal. Before the addition of FeS2 and FeS to the coal samples, the coal production amount was not much different below 80–90°C, and then, the gap gradually widened. Under the same temperature condition of coal, carbon monoxide (CO) production basically occurred first as the sulfur content increased. When FeS2 and FeS were added, the sulfur content of the coal samples was 3 and 4%, respectively, and the production of CO and ethene (C2H4) was the largest. Although the peak areas of aliphatic hydrocarbon, aromatic hydrocarbon, hydroxyl group, and carbonyl group in the coal samples with FeS were different, they all reached their maximum value when the sulfur content was 4%.

Investigation of the qualities of some promising oils of the Absheron oil and gas region

The article presents the characteristics of characteristic oils of the Apsheron oil and gas region, as well as the hydrocarbon composition of light and oil fractions. Oils of the Apsheron oil and gas region in terms of light fractions, sulfur content, and density are comparable to marketing grades of oils. The standards for prices are: graded crude oil WTI, Light Sweet, Brent, and Russian oils Sokol, Urals, Siberian Light are approaching them. We have studied in detail the yields and hydrocarbon composition of light and oil fractions of oils from the Apsheron oil and gas region. To obtain oils with a high viscosity index, studies were carried out to change the structure of oil fractions using hydrogen using the example of oil fractions of Azeri oil. Due to the significant content of aromatic hydrocarbons, schemes for the processing of oil fractions have been developed, including selective purification of distillates, dewaxing (except for Guneshli oil), as well as hydrocatalytic treatment in a severe mode in the presence of industrial Russian catalysts. As a result, it was possible to obtain API group I oils, according to the viscosity classification corresponding to SAE 20 and SAE 30. Thus, a study of the qualities and hydrocarbon composition of oils from the Absheron oil and gas region showed that these oils are characterized by a high content of light fractions, low density, and low sulfur content. According to these indicators, these oils correspond to the marker oils. In order to obtain base oils with a viscosity index of ≥90 and an aromatic hydrocarbon content of ≥10, a traditional refining method was used: selective refining, dewaxing, and severe hydrotreating.

Advances in Carbon-Based Nanocomposites for Deep Adsorptive Desulfurization

The ultra-low sulfur diesel (ULSD) is required to comply with stricter government policy on low sulfur content of transportation fuels. Better knowledge of the different factors that concern deep desulfurization of fuels is necessary to achieve ultra-low sulfur content and cheaper way of producing ULSD. Both the capital and operating cost of the adsorptive desulfurization process is cheaper compare to the conventional hydroprocessing. In the future, the need to produce more volume of fuels with very low sulphur content from low-grade feedstocks like heavy oil and light cycle oil in order to meet up with the global demand for sulphur-free fuels is pertinent. Several on-going researches are pointing to the use of adsorbents for removal of sulfur compounds from hydrocarbon refining stream. In this chapter, varieties of carbon nanomaterials suitable for adsorptive desulfurization are discussed. If the active lifetime, where the capacity of the adsorbents are adequate, the approach is practically feasible for commercial application.

Effect of pyrolysis temperature on desulfurization performance of high organic sulfur low rank coal

The sulfur in coal not only influences the coke quality but also pollutes the environment during the combustion. The desulfurization of high organic sulfur coal is a key issue in coal cleaning science. As the pyrolysis has been used in low-rank coal conversion to obtain gas/liquid products and coal char, the desulfurization effects of pyrolysis on the low-rank coal with high organic sulfur requires further studies. This study investigated the desulfurization performance of high organic sulfur low-rank coal by the pyrolysis and the changes in the coal calorific value and sulfur forms during the pyrolysis. The XPS was applied to analyze the changing regulation of sulfur that forms on coal surface. The results indicated certain amount of FeS was newly created during the pyrolysis and high amounts of sulfate sulfur was transferred to pyrite sulfur and formed more FeS2 when compared to the distribution of raw coal. The total sulfur content of coal was reduced from 2.32% for raw coal to 1.68% for 700 °C pyrolysis coal and then the pyrolysis temperature had little effect on the sulfur content. The net calorific value (at constant volume and air-dry basis) was increased from 17.38 kJ for raw coal to 24.35 kJ for 700 °C pyrolysis coal. The pyrolysis temperature of 700 °C may be the best pyrolysis temperature for both low sulfur content and high calorific value.

Advances in Carbon-Based Nanocomposites for Deep Adsorptive Desulfurization

The ultra-low sulfur diesel (ULSD) is required to comply with stricter government policy on low sulfur content of transportation fuels. Better knowledge of the different factors that concern deep desulfurization of fuels is necessary to achieve ultra-low sulfur content and cheaper way of producing ULSD. Both the capital and operating cost of the adsorptive desulfurization process is cheaper compare to the conventional hydroprocessing. In the future, the need to produce more volume of fuels with very low sulphur content from low-grade feedstocks like heavy oil and light cycle oil in order to meet up with the global demand for sulphur-free fuels is pertinent. Several on-going researches are pointing to the use of adsorbents for removal of sulfur compounds from hydrocarbon refining stream. In this chapter, varieties of carbon nanomaterials suitable for adsorptive desulfurization are discussed. If the active lifetime, where the capacity of the adsorbents are adequate, the approach is practically feasible for commercial application.

Improvement of the Content and Uptake of Micronutrients in Spring Rye Grain DM Through Nitrogen and Sulfur Supplementation

The aim of this field experiment was to analyze the influence of different nitrogen and sulfur doses on yield as well as the content and uptake of iron (Fe), manganese (Mn), copper (Cu) and zinc (Zn) by spring rye grain. The study was conducted in south-eastern Poland (2009–2011) on Cambisols (WRB 2015), in conditions of low sulfur content in soil. The experiment included four doses of N fertilization (0, 30, 60 and 90 kg ha−1) and two doses of S supplementation (0 and 40 kg ha−1). The analysis showed that fertilization with N and S had a positive effect on the studied features of spring rye. The highest grain yields were found after use of 90 kg N ha−1. The grain of rye fertilized with these doses of N was characterized by the highest concentration and uptake of tested microelements. The supplementation of sulfur in a dose of 40 kg S ha−1 improved the nitrogen effect, because the rye grain yield and the content and uptake of micronutrients (except Mn) by rye grain dry mass increased. The highest yield of spring rye grain and accumulation of Mn and Zn and intake of Mn, Zn and Cu by grain dry mass (DM) were obtained in the vegetation season of 2011, which was characterized by an optimal rainfall distribution. The highest accumulation of Fe and Cu and intake of Fe were obtained in the vegetation season of 2009. Significant correlations were found also between grain yield and the content and uptake of all studied micronutrients. The supplementation of NPK fertilization with sulfur can be a good means of agronomic biofortification for spring rye in order to increase the content and uptake of Fe, Mn, Zn and Cu.

Reductive Smelting of Neutralized Red Mud for Iron Recovery and Produced Pig Iron for Heat-Resistant Castings

The chemical and mineral composition of the red mud from the Ural Aluminum Plant were studied by XRF, XRD, and Mössbauer spectroscopy. Experiments on reductive smelting of red mud were carried out in a range of temperatures (1650–1750 °C) to recover iron from the aluminum production waste with maximum efficiency. It was found that it is possible to obtain pig iron with a high content of titanium, phosphorus, and vanadium, and low sulfur content. The efficiency of iron recovery at 1750 °C was found to be around 98%. Thermodynamic calculations were carried out to assist in finding the optimal conditions for the process (e.g., carbon content, furnace temperature, slag liquidus temperature). It was also found that the pig iron phase obtained at 1650 to 1700 °C is not separated from the slag phase into ingot compared with the sample obtained at 1750 °C. Pig iron obtained at 1750 °C can be used to produce molds for the steel-casting equipment.