Features of the Behavior of Precious Metals in the Sulfide-Alkaline Leaching of Arsenic-Antimony Concentrates

Для минерально-сырьевой базы металлургии цветных и благородных металлов месторождения полиметаллических руд являются основным источником сырья. На фоне глобальной тенденции к снижению доли богатых руд в общем объеме добычи и переработки и ухудшению качественных характеристик рудного сырья ведется отработка запасов руд, содержащих в виде примесей мышьяк и сурьму. Авторами была изучена возможность применения ASL‑технологии при атмосферном давлении для гидрометаллургического кондиционирования низкокачественного медного концентрата. Исследования осуществлялись на флотационном концентрате следующего состава (%): 16,1 Cu; 5,3 Zn; 23,8 Fe; 0,84 Pb; 1,36 As; 0,21 Sb; 1,94 SiO2; 0,82 Al2O3, до 24,0 г/т Ag, до 4,0 г/т Au. В результате выполненных исследований были выявлены особенности поведения благородных металлов в сульфидно-щелочной среде в процессе выщелачивания мышьяково-сурьмянистых концентратов Учалинского ГОКа. Установлена доминирующая роль сульфида натрия при образовании полисульфид- и тиосульфат-ионов, выполняющих роль окислителей золота и серебра. Анализ кинетических показателей свидетельствует о лимитировании процесса выщелачивания благородных металлов скоростью химической реакции при отсутствии внутридиффузионных ограничений, обусловленных возможной пассивацией теннантита, формирующимися вторичными сульфидами меди. Определены минимальные пороговые концентрации сульфида и полисульфидов, при которых возможен переход в раствор выщелачивания золота и серебра: для сульфида более 20 г/л‑1, для полисульфидов более 2 М. При проведении ASL‑процесса с указанными параметрами кек выщелачивания представляет собой кондиционный медно-цинковый концентрат, содержащий 0,2 % мышьяка и благородных металлов до 100 г/т. Потери благородных металлов в ходе процесса отсутствуютFor the mineral resource base of metallurgy of non-ferrous and noble metals, deposits of polymetallic ores are the main source of raw materials. Against the backdrop of a global trend towards a decrease in the share of rich ores in the total volume of mining and processing, and a deterioration in the quality characteristics of ore raw materials, ore reserves containing arsenic and antimony as impurities are being developed. The authors studied the possibility of using ASL technology at atmospheric pressure for hydrometallurgical conditioning of low-quality copper concentrate. The studies were carried out on a flotation concentrate of the following composition (%): 16.1 Cu; 5.3 Zn; 23.8 Fe; 0.84 Pb; 1.36 As; 0.21 Sb; 1.94 SiO2; 0.82 Al2O3, up to 24.0 g/t Ag, up to 4.0 g/t Au. As a result of the studies carried out, the features of the behavior of noble metals in the sulfide-alkaline environment during the leaching of arsenic-antimony concentrates of the Uchalinsky GOK were revealed. The dominant role of sodium sulfide in the formation of polysulfide and thiosulfate ions, which act as oxidizers for gold and silver, has been established. An analysis of the kinetic parameters indicates that the process of leaching of precious metals is limited by the rate of a chemical reaction in the absence of intradiffusion restrictions due to the possible passivation of tennantite by the formed secondary copper sulfides. The minimum threshold concentrations of sulfide and polysulfides were determined, at which a transition to the gold and silver leaching solution is possible: for sulfide more than 20 g/l‑1, for polysulfides more than 2 M. The obtained product after ASL process was copper-zinc concentrate containing 0.2 % arsenic and precious metals up to 100 g/t. There are no losses of precious metals during the proces

Mutations in transcription factor as rare causes of diabetes in pregnancy

MODY1 and MODY3 represent rare causes of diabetes in pregnancy. Establishing a molecular diagnosis of MODY1 or MODY3 during pregnancy may be important for minimizing risk of perinatal complications and for improving glycemic control after pregnancy. The objective of the study was to evaluate the contribution of mutations in HNF4A and HNF1A genes in development of diabetes in pregnancy and to describe clinical characteristics of diabetes in pregnancy associated with these mutations. 230 pregnant women (20-43 years) with different type of glucose intolerance complicated during their current pregnancy were included in the study. A custom NGS panel targeting 28 diabetes causative genes was used for sequencing. Heterozygous mutations in HNF4A and HNF1A genes were detected in 3% of cases. Mutations p.I271T in HNF4A gene and p.L148F, p.Y265C, p.G288W in HNF1A gene were novel. This study includes a description of patients with pregnancy diabetes due to mutations in hepatocyte nuclear factors

Improving the Algorithm of Choosing Spacing and Number of Stiff Supports Against A Concentrated Force in Steel-concrete Beams

A steel-concrete beam was taken as the study object. The algorithm of selecting the number of stiff supports for the steel-concrete beam loaded with a concentrated lateral force in the middle of the span has been refined. Stiff supports served to join the steel strip with concrete to ensure their joint performance. The algorithm was refined based on the condition of equality of the longitudinal force in the steel strip from the action of the calculated load and the maximum longitudinal force obtained after setting the supports. In this case, the longitudinal forces in all stiff supports, as well as the spacing of the stiff supports should be the same. A disadvantage of the known algorithm consists in the complexity of determining the coefficient φb2 taking into account the effect of long-term concrete creep on the element deformation without cracks. This coefficient fluctuates widely and depends on many factors. Besides, it is also insufficiently studied. Calculations for determining the number and spacing of stiff supports in a steel-concrete beam were conducted according to the proposed algorithm and in the Lira software package. The forces acting on the supports and spacing of the supports were the same. The force acting in the support was 8941.5 N. When selecting characteristics of the steel-concrete beam, maximum longitudinal force in the steel strip was obtained. The longitudinal force amounted to 35726 N. The same longitudinal force was obtained from the diagram of longitudinal forces obtained after setting the supports. This study was aimed at improving the design of steel-concrete beams. A rational number and placement of stiff supports ensure savings: the required amount of building materials is reduced and their cost is reduced due to cutting labor costs for their manufacture and operatio

Construction of an Algorithm for the Selection of Rigid Stops in Steel­concrete Beams Under the Action of A Distributed Load

An algorithm has been developed to select rigid stops in steel-concrete beams under the action of distributed load. Concrete is connected rigidly to a steel sheet in order to perform the joint operation of the concrete and steel sheet. Such a connection in the beam is provided by rigid stops that prevent shifting efforts in the concrete and steel contact area. The efforts are determined through the turning angles between the two adjacent sections of the beam. A graph-analytical method for determining movements is used to determine the turning angles. In determining the deformations of a steel-concrete beam, the calculation is based on the reduced rigidities of cross-sections.The purpose of this study is to optimize the structure of a steel-concrete beam by selecting the rational number and arrangement of rigid stops. This optimization would allow a more rational utilization of the structure's material ‒ concrete and steel. That would reduce the cost of operations and the quantity of materials required in the production, installation, and operation of the considered structures.An earlier proposed algorithm for the selection of rigid stops in steel-concrete beams under the action of a concentrated force has been expanded for the case of an evenly distributed load. When selecting the number of rigid stops, it is assumed that the magnitude of the distributed load acting on a beam, the mechanical characteristics of materials (steel and concrete), as well as the span of the beam and the size of its cross-section, are kNown. In contrast to the beams with a concentrated force in the middle, where the forces abide by a linear law, in the beams with an evenly distributed load the efforts in a steel strip change in line with a square parabola. Therefore, while the same step has been obtained for stops, it is not possible to achieve a situation at which efforts in all stops have the same valu

Establishing the Influence of Technical and Technological Parameters of Milking Equipment on the Efficiency of Machine Milking

One of the tasks that imply increasing the milk productivity of cows is to create optimal maintenance conditions that ensure the increased use of the genetic potential of cattle based on the implementation of engineering and technological solutions. A mathematical model has been built that links the technical and technological parameters of the vacuum system of milking equipment, namely, the value of the working vacuum P, the pulsation frequency n, the ratio of pulsation cycles, and the tension strength of milking rubber FH to cows' milk yield rate V. The range of milking plant operating parameters for milking in the milk line has been determined, at which the milk yield rate is maximum: P=52 kPa, n=57.6–58.8 min–1, δ=0.59–0.64, FH=59.3–60.4 H. Under these parameters, the milk yield rate is V=1.48–1.53 l/min. The results of the multifactor experiment have helped construct an adequate mathematical model of the second order, which confirms the theoretical dependence of the influence of the technical and technological parameters of the vacuum system of milking equipment on milk yield rate and the air flow of the milking machine. Analysis of the mathematical model has made it possible to establish the rational structural and technological parameters for the vacuum system of a milking machine: the value of the working vacuum, P=50.6 kPa; pulsation frequency, n=55.9 min–1, the ratio of pulsation cycles and the tension force of milking rubber FH=64.8 H. Under these parameters, the milk yield rate is maximum: V=1.47–1.52 l/min; the air flow consumption of the milking machine is Q=2.19 m3/h. The mathematical model built fully reveals the influence of technical and technological parameters of milking equipment on the efficiency of machine milking. Owing to this, the issue related to the rational choice of equipment is resolved