scholarly journals Pressure Oxidation of Arsenic (III) Ions in the H3AsO3-Fe2+-Cu2+-H2SO4 System

Metals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 975
Author(s):  
Kirill Karimov ◽  
Denis Rogozhnikov ◽  
Oleg Dizer ◽  
Maksim Tretiak ◽  
Sergey Mamyachenkov ◽  
...  
Keyword(s):  
Oxygen Pressure ◽  
Catalytic Effect ◽  
Mineral Resources ◽  
Effect Of Temperature ◽  
Stable Form ◽  
Low Grade ◽  
Hydrothermal Precipitation ◽  
Ferric Arsenates ◽  
Oxidation Efficiency ◽  
Positive Effect

The processing of low-grade polymetallic materials, such as copper–zinc, copper–lead–zinc, and poor arsenic-containing copper concentrates using hydrometallurgical methods is becoming increasingly important due to the depletion of rich and easily extracted mineral resources, as well as due to the need to reduce harmful emissions from metallurgy, especially given the high content of arsenic in ores. Ferric arsenates obtained through hydrothermal precipitation are the least soluble and most stable form of arsenic, which is essential for its disposal. This paper describes the investigation of the oxidation kinetics of As (III) ions to As (V) which is required for efficient purification of the resulting solutions and precipitation of low-solubility ferric arsenates. The effect of temperature (160–200 °C), the initial concentration of Fe (II) (3.6–89.5 mmol/dm3), Cu (II) (6.3–62.9 of mmol/dm3) and the oxygen pressure (0.2–0.5 MPa) on the oxidation efficiency of As (III) to As (V) was studied. As (III) oxidation in H3AsO-Fe2+-Cu2+-H2SO4 and H3AsO-Fe2+-H2SO4 systems was controlled by a chemical reaction with the apparent activation energy (Ea (≈84.3–86.3 kJ/mol)). The increase in the concentration of Fe (II) ions and addition of an external catalyst (Cu (II) ions) both have a positive effect on the process. When Cu (II) ions are introduced into the solution, their catalytic effect is confirmed by a decrease in the partial orders, Fe (II) ions concentration from 0.43 to 0.20, and the oxygen pressure from 0.95 to 0.69. The revealed catalytic effect is associated with a positive effect of Cu (II) ions on the oxidation of Fe (II) to Fe (III) ions, which further participate in As (III) oxidation. The semi-empirical equations describing the reaction rate under the studied conditions are written.

scholarly journals Influence of reaction conditions on the ozonation process

2013 ◽  
Vol 6 (2) ◽  
pp. 168-172 ◽  
Author(s):  
Lenka Sumegová ◽  
Ján Derco ◽  
Michal Melicher
Keyword(s):  
Methylene Blue ◽  
Activated Carbon ◽  
Radical Reaction ◽  
Effect Of Temperature ◽  
Ph Range ◽  
Oxidation Efficiency ◽  
Increasing Temperature ◽  
Positive Effect ◽  
Ozonation Process ◽  
Granulated Activated Carbon

Abstract This paper is focused on the influence of granulated activated carbon (GAC) and zeolite as catalysts as well as influences of temperature and pH on the ozonation process. From obtained results it can be concluded that the addition of granulated activated carbon and zeolite to model wastewater has a positive effect on the efficiency and degradation rate of methylene blue oxidation with ozone. The highest oxidation efficiency was observed in the alkaline pH range for which radical reaction mechanism of ozone is characteristic. From the results obtained during the study of the effect of temperature on the ozonation process it follows that both the efficiency and the rate of oxidation of methylene blue grow with increasing temperature.

A breakthrough method for the recycling of spent lithium-ion batteries without pre-sorting

2021 ◽  
Author(s):  
Jialiang Zhang ◽  
Guoqiang Liang ◽  
Cheng Yang ◽  
Juntao Hu ◽  
Yongqiang Chen ◽  
...  
Keyword(s):  
Lithium Ion Batteries ◽  
Lithium Ion ◽  
Mineral Resources ◽  
Low Grade ◽  
Valuable Metals

Inspired by the process of "metallurgy first and then beneficiation" for disposing low-grade and complex mineral resources, we proposed a breakthrough method to recover valuable metals from spent entire lithium-ion...

Effect of Temperature on Column Bioleaching of a Refractory Gold Ore

2013 ◽  
Vol 825 ◽  
pp. 352-355 ◽  
Author(s):  
Zeng Ling Wu ◽  
Zhong Sheng Huang ◽  
Ren Man Ruan ◽  
Shui Ping Zhong ◽  
Brenda K.C. Chan
Keyword(s):  
Sulfide Oxidation ◽  
Effect Of Temperature ◽  
Low Grade ◽  
Key Factors ◽  
Gold Extraction ◽  
Gold Ores ◽  
Fraction Distribution ◽  
Higher Temperature ◽  
Liberation Analysis ◽  
Main Factor

Low-grade, finely disseminated refractory sulfide gold ores associated with high arsenic are ubiquitous resources all over the world. Since heap bio-oxidation is an economic and promising biotechnology to recover gold, low grade, high organic carbon and arsenic bearing gold ores from Zhesang Mines in China were chosen for this purpose to study the key factors that would affect biooxidation. Pyrite and arsenopyrite (particle size 0.002-0.22 mm) were the main minerals from Mineral Liberation Analysis (MLA). Column biooxidation and cyanidation of mineral size < 10 mm were evaluated for its potential for gold extraction. Results showed that temperature was the main factor influencing sulfide oxidation. 58-67 % of sulfide was oxidized at 35-45°C after > 240 days of biooxidation with mixed mesophiles, while higher sulfide-S dissolution (77%) was obtained at 60°C. Sulfide-S fraction distribution revealed higher mineral decomposition, finer fractions and eventually higher sulfide oxidation at 60°C. Jarosite and scorodite were found from the residues at 60°C by SEM and EDX, which implies higher temperature accelerated arsenic precipitation. No elemental sulfur was detected during the biooxidation at 35-60°C. After bio-oxidation, column cyanidation was successfully demonstrated recovery of gold from the residues, with gold extraction rate reaching 66%.

scholarly journals Geology and Mineral Resources of Phalamdada-Dhuwakot Section of West-Central Nepal, Lesser Himalaya

2018 ◽  
pp. 59-64
Author(s):  
Arjun Bhattarai ◽  
Kabiraj Paudyal
Keyword(s):  
Mineral Resources ◽  
Geological Mapping ◽  
Metamorphic Rocks ◽  
Low Grade ◽  
Lesser Himalaya ◽  
Central Nepal ◽  
West Central ◽  
Metallic Mineral ◽  
Geological Control ◽  
Core Part

Geological mapping was carried out along the Phalamdanda-Dhuwakot section of west-central Nepal in the Lesser Himalaya. The aim of geological mapping was to prospect the metallic mineral resources in the area especially to assess the geological control of mineralization as prognostic mapping and study the genesis of mineralization. The area has developed low-grade metamorphic rocks of the Nawakot Group. Geological rock units like the Kuncha Formation, Fagfog Quartzite, Dandagaon Phyllite, Nourpul Formation and Dhading Dolomite are mapped in the area. Jal Bhanjyang Thrust carries the more older rocks of the Nourpul Formation over the Dhading Dolomite. The area is highly deformed as indicated by presence of folds. Outliers of Fagfog Quartzite and Dhading Dolomite are developed at the core part of the syncline. Phalamdada iron and Anbu Khaireni as well as Dharapani copper are the major metallic deposits reported in the area. Both deposits are considered as the syngenetic in nature. Bulletin of Department of Geology, vol. 20-21, 2018, pp:59-64

scholarly journals Lactobacillus Rhamnosus GG Affects the BDNF System in Brain Samples of Wistar Rats with Pepsin-Trypsin-Digested Gliadin (PTG)-Induced Enteropathy

Nutrients ◽  
2020 ◽  
Vol 12 (3) ◽  
pp. 629
Author(s):  
Antonella Orlando ◽  
Guglielmina Chimienti ◽  
Angela Maria Serena Lezza ◽  
Vito Pesce ◽  
Isabella Gigante ◽  
...  
Keyword(s):  
Nervous System ◽  
Adaptive Response ◽  
Wistar Rats ◽  
Lactobacillus Rhamnosus ◽  
Low Grade ◽  
Lactobacillus Rhamnosus Gg ◽  
Curative Effect ◽  
Low Grade Inflammation ◽  
The Brain ◽  
Positive Effect

Celiac disease (CD) presents as chronic low-grade inflammation of the small intestine often characterized by psychiatric comorbidities. The brain-derived neurotrophic factor (BDNF), which we have shown to be reduced in the serum of CD patients, acts as the bridge between immune activation and the nervous system adaptive response. Since Lactobacillus has been shown to upregulate BDNF, this study aimed to evaluate whether the administration of Lactobacillus rhamnosus GG (L.GG) could positively affect the brain BDNF system in rats mimicking the CD lesions. Data have shown that the administration of pepsin-trypsin digested gliadin (PTG) and L.GG alter the levels of mature BDNF (mBDNF), as evaluated by Western blotting. PTG provoked a reduction of mBDNF compared to controls, and a compensatory increase of its receptor TrkB. L.GG induced a slight positive effect on mBDNF levels under normal conditions, while it was able to rescue the PTG-induced reduced expression of mBDNF. The curative effect of L.GG was finely tuned, accompanied by the reduction of TrkB, probably to avoid the effect of excessive BDNF.

Sulfur Content Reduction and Iron Grade Improvement of V-Ti Magnetite Concentrate by Combining Reverse Flotation and Magnetic Separation

2012 ◽  
Vol 524-527 ◽  
pp. 1115-1123 ◽  
Author(s):  
Jiu Shuai Deng ◽  
Shu Ming Wen ◽  
Shao Jun Bai ◽  
Mei Fang Xie ◽  
Hai Ying Shen
Keyword(s):  
Magnetic Separation ◽  
Sulfur Content ◽  
Ph Value ◽  
Mineral Resources ◽  
Open Circuit ◽  
Low Grade ◽  
Reverse Flotation ◽  
Magnetic Intensity ◽  
Magnetite Concentrate ◽  
Iron Grade

For low-grade iron ore, smelting costs and resource wastage will be increased. Product quality of such ore is affected adversely by an excessive amount of sulfur. This also causes environmental pollution. In accordance with the vanadium-titanium (V-Ti) magnetite concentrate properties with low iron grade and high sulfur content, the joint process of magnetic separation and flotation was carried out. Magnetic separation was conducted to increase the iron grade, while reverse flotation was used to reduce sulfur content. Results show that the feeding mainly contains titanomagnetite, hematite, and pyrite. The sulfur was primarily found in pyrite. The separation effect was influenced by the grinding fineness, magnetic intensity, collector type and dosage, and pH value. At a grinding fineness of −45 μm accounting for 87%, most of the iron minerals exhibited monomer dissociation. An open-circuit experiment was carried out under the best conditions of magnetic intensity, as well as collector and modifier dosage. Good experimental results were obtained as follows: the iron grade increased to 57.17%, iron recovery was 89.94%, sulfur content decreased from 0.66% to 0.26%, reverse flotation of sulfur foam concentrate contained almost 15.68% sulfur, the upgrade ratio was about 23, and the cobalt in the sulfur concentrate was enriched 20-fold. A method for improving the comprehensive utilization level and effect of mineral resources is provided in this study.

scholarly journals Rare Earth Elements and Other Critical Metals in Deep Seabed Mineral Deposits: Composition and Implications for Resource Potential

Minerals ◽  
2018 ◽  
Vol 9 (1) ◽  
pp. 3 ◽  
Author(s):  
Sang-Joon Pak ◽  
Inah Seo ◽  
Kyeong-Yong Lee ◽  
Kiseong Hyeong
Keyword(s):  
Rare Earth ◽  
Deep Sea ◽  
Mineral Resources ◽  
Rare Earth Oxide ◽  
Economic Feasibility ◽  
Mineral Deposits ◽  
Low Grade ◽  
Ion Adsorption ◽  
Critical Metals ◽  
Deep Sea Sediment

The critical metal contents of four types of seabed mineral resources, including a deep-sea sediment deposit, are evaluated as potential rare earth element (REE) resources. The deep-sea resources have relatively low total rare earth oxide (TREO) contents, a narrow range of TREO grades (0.049–0.185%), and show characteristics that are consistent with those of land-based ion adsorption REE deposits. The relative REO distributions of the deep-seabed resources are also consistent with those of ion adsorption REE deposits on land. REEs that are not part of a crystal lattice of host minerals within deep-sea mineral deposits are favorable for mining, as there is no requirement for crushing and/or pulverizing during ore processing. Furthermore, low concentrations of Th and U reduce the risk of adverse environmental impacts. Despite the low TREO grades of the deep-seabed mineral deposits, a significant TREO yield from polymetallic nodules and REE-bearing deep-sea sediments from the Korean tenements has been estimated (1 Mt and 8 Mt, respectively). Compared with land-based REE deposits, deep-sea mineral deposits can be considered as low-grade mineral deposits with a large tonnage. The REEs and critical metals from deep-sea mineral deposits are important by-products and co-products of the main commodities (e.g., Co and Ni), and may increase the economic feasibility of their extraction.

scholarly journals The effect of temperature upon radioactive disintegration

1912 ◽  
Vol 86 (586) ◽  
pp. 240-253 ◽  
Keyword(s):  
High Temperature ◽  
High Temperatures ◽  
Systematic Investigation ◽  
Effect Of Temperature ◽  
Active Matter ◽  
Radium Emanation ◽  
Γ Rays ◽  
Method Of Measurement ◽  
Positive Effect

Within the last few years the influence of high temperature on the activity of radium emanation, of the active deposit, and of radium C has been examined in detail by several authors. The conclusions arrived at have been conflicting, some workers affirming a positive effect of tem­perature, others denying it. This lack of agreement is due, however, to a difference in the method of measurement of the active matter under investigation. Those workers who measured the activity by γ-rays are all agreed that temperature has no effect whatever, while those who measured by β-rays found always an effect of some kind, in many cases of considerable magnitude, and often, indeed, of a very surprising nature. While, however, the fact that there is a β-ray effect is admitted by all, there is still a lack of agreement between the results of the experiments of different workers, and even of different experiments of the same worker, which is hardly to be expected if the effects were due to a definite change in the properties of the disintegrating atoms at high temperatures. In view, therefore, of the uncertainty which has arisen on a point of such great theoretical importance, a systematic investigation was necessary to obtain definite results, whether positive or negative. This the author, at the request of prof. Rutherford, has carried out.

Observations on the ecology of the cloths moths Tineola bisselliella (Humm) and Tinea pellionella L in a bulk wool store.

1959 ◽  
Vol 7 (1) ◽  
pp. 39 ◽  
Author(s):  
KHL Key ◽  
IFB Common
Keyword(s):  
Abundance Ratio ◽  
Effect Of Temperature ◽  
Flight Period ◽  
Low Grade ◽  
Additional Species ◽  
Free Air ◽  
Microclimatic Conditions ◽  
C 50 ◽  
Number Of Males ◽  
Tineola Bisselliella

Observations on the behaviour and abundance of Tineola bisselliella and Tinea pellionella were made during 1942 and 1943 in a Brisbane wool store which remained relatively undisturbed for more than three years. The store contained c. 10,000 strongly compressed. jute-covered "double dumps" of low-grade, greasy wool, stacked in large bays separated by passages. Microclimatic conditions were more equable than in the open and very favourable to the moths. Substantial vertical gradients in temperature and relative humidity resulted from insolation of the roof, but there was little horizontal differentiation. The wool tended to buffer fluctuations of these elements, both in the free air spaces and, still more, within the dumps. Larvae of Tinea were confined to loose wool protruding through breaches in the jute pack. Tineola occurred both there and within the surface 2 in. of the compressed wool under the pack. By 1943 there was estimated to be an average of c. 50 well-grown larvae per dump. Adult moths could always be seen sitting or running on the dumps throughout the stacks. The moth populations were studied by sampling with tanglefoot traps in the passages and stacks. Both species had a flight period around dusk, about half the 24-hr catch being made during the 3 hr after sunset. The peak fell earlier on cool evenings. A regression of activity on mean flight period temperature was established, a rise from 65 to 80�F doubling the catch. Females rarely fly: they normally constituted only c. 0.3 per cent, of the catch, although the sex ratio in the population as a whole was probably about 23 : 19 for Tineola and 13 : 49 for Tinea. The density of moths in flight was approximately equal in stacks and passages at a, given level, but usually increased with height. By correcting the daily catches for the effect of temperature on activity, plots of adult abundanoe against time were constructed. The two species fluctuated in almost identical fashion. Numbers were low in winter, high in spring and summer, with an indication of two to three generations per annum. From the beginning of 1943 a great decline in abundance set in, the peak for that year being a small fraction of that for 1942. The braconid Apanteles carpatus, a parasite of both moths, was also taken on the traps. It had a flight period at about the time of the daily temperature maximum. A regression of activity on temperature showed a near-quadrupling of the catch for a rise from 70 to 85�F. A plot of adult abundance was derived as for the moths. It showed a single seasonal peak falling after the moth peaks. Several overlapping generations are postulated. The abundance ratio of Apanteles to moths rose steadily from spring to autumn in each year, but showed close agreement for corresponding seasons of the two years: there is no reason to ascribe the 1943 decline in moth numbers to the parasite. A spider, Uloborus geniculatus, became very abundant during 1943 and is believed to have been responsible for the decline of the moths, which represented its main source of food. Over the relevant period the percentage of female moths in the catch increased 40-fold, presumably as a result of the differential removal of the active males by the spider. It is calculated that in this way the number of males was reduced, by November 1943, to about 1/45 of what it would otherwise have been. The spider probably also caught adult Apanteles. It is concluded that, apart from effects of the introduction of additional species, the moths and spiders would ultimately establish some sort of equilibrium, probably at a rather low level of density. The factors favouring Uloborus in its limiting role are discussed.

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