scholarly journals Effect of Microwave Pretreatment on Leaching of Tetrahedrite

2021 ◽  
Vol 906 (1) ◽  
pp. 012111
Author(s):  
Ingrid Znamenácková ◽  
Silvia Dolinská ◽  
Slavomír Hredzák ◽  
Vladimir Cablík

Abstract In mineral processing, the use of microwave radiation is important especially in pre-treatment processes. At present, there is an acceleration of processes as well as an increase in the efficiency of metal recovery. One of the main problems in copper recovery from complex sulphide ores is the removal of impurities such as antimony, arsenic, mercury. In the hydrometallurgical processing scheme, the key step is the leaching. The extraction process can be influenced by the selection of suitable leaching reagents or by suitable pre-treatment of the ore. The article describes the effect of microwave radiation on the leaching Sb, As and Hg of tetrahedrite and tetrahedrite concentrate. The samples were irradiated at the power 900 W for 30 seconds. The leaching of irradiated and non-irradiated samples was realized in an alkaline sodium sulphide. The positive effect of microwave radiation was confirmed by an increase in the recovery of Sb and As already after 15 min of extraction. After microwave leaching of irradiated tetrahedrite samples, the yield of Sb was 43.2 %, in irradiated tetrahedrite concentrate, the yield of Sb was 81.3 %.

2014 ◽  
Vol 543-547 ◽  
pp. 1896-1900
Author(s):  
Deng Zhou ◽  
Wen Huang He ◽  
Tao Tao Wu

This Compared with the traditional text classification model, the Tibetan text classification based on N-Gram model has adopted N-Gram model in terms of the level of word. In other words, during the text classification, word segmentation is not required. Also, feature selection and abundant pre-treatment processes are avoided. This paper not only carried out profound research on N-Gram models, but also discusses the selection of parameter N in the model by adopting Naïve Bayes Multinomial classifier.


2000 ◽  
Vol 41 (10-11) ◽  
pp. 117-123 ◽  
Author(s):  
C. Visvanathan ◽  
P. Svenstrup ◽  
P. Ariyamethee

This paper presents a case study of a natural gas production site covering various technical issues related to selection of an appropriate Reverse Osmosis (RO) system. The long-term field experience indicates the necessity of the selection of appropriate pretreatment systems for fouling-free RO operational conditions. The produced water has a variety of impurities such as oil and grease, process chemicals used for corrosion and scaling control, and dehydration of natural gas, etc. This situation leads to a complicated and extremely difficult task for a membrane specialist to design RO systems, especially the pre-treatment section. Here as part of the pretreatment selection, two types of UF membrane modules viz. spiral wound and hollow fibre, with MWCO of 8000 and 50,000 Dalton respectively, were tested in parallel with NF membranes of the spiral wound type with MWCO 200 Dalton. The UF permeate is used as feed for RO compatibility testing. Both configurations of UF failed to be compatible, due to irreversible fouling of the RO membrane. The NF membrane, however, showed interesting results, due to membrane stability in terms of cleaning and fouling. The NF plant with 50% capacity gave a recovery of 75% and the RO plant gave a recovery of 60% versus the expected 92–95%. The long-term tests have indicated that the reminder of the membranes could be installed to achieve full capacity of the plant. This study also demonstrates the importance of selection of proper pre-treatment set-up for the RO system design.


2012 ◽  
Vol 441 ◽  
pp. 640-644
Author(s):  
Ke Jie Fu ◽  
Li Sheng Yang ◽  
Chang Sheng Feng ◽  
Liang Chen

A detecting method for toxic flame retardant finishing agent tris-(2,3-dibromopropyl) -phosphate (TRIS for short) in textiles was studied. In the method, an acetonitrile ultrasound-assisted extraction process was included in sample pre-treatment, and HPLC/DAD was used in the separation and identification of extractives. After that, the conditions of pre-treatment and chromatograph were optimized. The results showed that the limit of detection (LOD) by this method (S/N10) is 1.0 mg/kg, its recovery ranged from 78.1% to 98.4%, and RSD of the precision test is 3.2%, of which all met the requirements for routine testing.


2021 ◽  
Vol 1037 ◽  
pp. 486-493
Author(s):  
Sergey Y. Zhachkin ◽  
Anatoly I. Zavrazhnov ◽  
Nikita A. Penkov ◽  
George V. Kudryavtsev ◽  
Paul V. Tsisarenko

One of the fundamental tasks in restoring the operability of cylinder liners is the application of a composite coating with a predetermined microhardness value. The authors have developed a technology for applying composite coatings based on iron on cylindrical surfaces, which makes it possible to vary the physical, mechanical and operational parameters of the formed iron-containing coating due to the planned selection of the deposition parameters. This eliminates the need for mechanical treatment of the applied coating, which is the reason for the high degree of rejection parts that undergo the iron-on operation. Contact interaction of the working tool with the formed layer of the composite coating has a positive effect on the value of its roughness.


1995 ◽  
Vol 31 (1) ◽  
pp. 237-247 ◽  
Author(s):  
Dick B. Janssen ◽  
Wim de Koning

The possibility of obtaining microbial cultures for the degradation of halogenated aliphatic hydrocarbons is mainly determined by the diversity and activity of catabolic enzymes that exist in nature. If a suitable organism is available, applications for the treatment of different waste streams can be developed. The relation between the kinetic parameters of the key enzymes and the properties of the organisms relevant for such applications is discussed, both for growth supporting and cometabolic degradation. When growth on a chlorinated aliphatic compound is possible, development of a biological remediation process is likely to be relatively easy. This is illustrated with the degradation of 1,2-dichloroethane, a synthetic compound that can be mineralized by specific cultures. Closely related compounds may be recalcitrant, which can be understood from an examination of the degradative pathways. The development of biological treatment processes based on cometabolic degradation is more demanding because selection of the proper organisms and maintaining them in the process are not straightforward. The range of compounds that can be degraded cometabolically is significantly larger. The potential of obtaining improved degradation by genetic adaptation and the use of biofilms is discussed.


2001 ◽  
Vol 44 (10) ◽  
pp. 121-128 ◽  
Author(s):  
J.A. Müller

Pre-treatment processes have been developed in order to improve subsequent sludge treatment and disposal. Disintegration of sludge solids in the aqueous phase changes the sludge structure and solubilizes organic matter. This paper provides an overview of the applications of wet disintegration in wastewater and sludge treatment. Applied disintegration techniques such as mechanical, thermal, chemical and biological methods are briefly described. The methods are compared regarding energy consumption, operational reliability and stage of development for application on wastewater treatment plants. Mechanical and thermal methods appear to be most suitable at this stage. The effects of pre-treatment on subsequent sludge treatment processes and the wastewater treatment are described. The performance of various methods is assessed. For the improvement of stabilization, mechanical and ozone treatment as well as thermal treatment perform best. Dewatering can be enhanced by thermal and freeze/thaw treatment. All methods show positive effects in the reduction of the number of pathogens. Pre-treatment leads to secondary effects like the generation of recalcitrant compounds and odor, which is mainly a problem of thermal and ozone treatment. The evaluation of capital and operational costs is difficult, because of the lack of full-scale experience. Especially thermal, freeze/thaw and biological treatments can be realized at low costs if the conditions are appropriate. Nevertheless, the economic efficiency has to be investigated critically for each individual application.


2004 ◽  
Vol 49 (10) ◽  
pp. 97-104 ◽  
Author(s):  
J.A. Müller ◽  
A. Winter ◽  
G. Strünkmann

The pre-treatment of sludges by disintegration will result in a number of changes in sludge properties. Floc destruction as well as cell disintegration will occur. This leads to an increase of soluble substances and fine particles. Furthermore, biochemical reactions may appear during or immediately after disintegration. The influence of disintegration of excess sludge on anaerobic digestion was studied in full scale. A stirred ball mill, an ultrasound disintegrator, a lysate centrifuge and ozone treatment were used. The results of the degradation process were compared to a reference system without pre-treatment. An enhancement of the degree of degradation of 7.4% to 20% was observed. The pollution of sludge water as well as the dewatering properties of the digested sludge were investigated. COD and ammonia in the sludge water were increased and a higher polymer demand was observed while the solid content after dewatering stayed almost unchanged. Based on these results the cost effectiveness has been assessed taking into account different conditions (size of WWTP, cost for disposal, etc.). Capital and energy costs are the main factors while the decrease in disposal costs due to the reduced amount of sludge is the main profit factor.


2019 ◽  
Vol 59 (7) ◽  
pp. 85-91
Author(s):  
Yulia A. Smyatskaya ◽  
◽  
Natalia A. Politaeva ◽  
Amira Toumi ◽  
◽  
...  

This article discusses the effect of the disintegration of the cell wall of the microalgae Chlorella sorokiniana on the output of the lipid fraction. The biomass of the microalgae Chlorella sorokiniana was grown under laboratory conditions in special photobioreactors at a temperature of 25 °C, with a constant aeration of a mixture of carbon dioxide and air at a rate of 1.5 liters/min, illumination 2200-2800 Lx. Nutrient medium for cultivation contained macro – and micronutrients for high-speed growth of microalgae. Selection of optimal cultivation parameters allows obtaining biomass with desired properties. Disintegration was carried out with the homogenization of biomass and under the influence of microwave radiation. Extraction of lipids was carried out on a semi-automatic extractor according to the Randall method, using organic solvents. The output of the lipid fraction without treatment was 10.18% after the destruction of the cell wall 14.45% with the homogenization of biomass and 13.85% under the influence of microwave radiation. A qualitative analysis of the lipid fraction, carried out under gas chromatography, obtained under various conditions showed that there was no significant difference in composition from the disintegration method. Lipid fractions (more than 50%) in both cases consist mainly of unsaturated fatty acids, of which irreplaceable unsaturated fatty acids constitute more than 18% for both samples. The residual biomass formed after the extraction of the lipid fraction can be used as fertilizer in the plant, for the manufacture of sorption materials for the purification of industrial water and as a biofuel. The purpose of this study was to study the effect of cell wall disintegration on the output of the lipid fraction and qualitative composition.


Author(s):  
Viktor MAZUR ◽  
Hanna PANTSYREVA ◽  
Kateryna MAZUR

In today's conditions of agrarian production in Ukraine, due to the rapid development of scientific and technological progress, a significant contribution belongs to scientific research based on world recognition, and publications in scientific journals indexed in the international science-computer databases of Web of Science and Scopus will lead to the possibility of modernization of modern science in agrarian institutions of higher education. It is established that realization of scientific researches in higher agricultural educational institutions is a prerequisite for increasing their competitiveness in the international scientific and educational space. So, agricultural universities, along with the implementation of their main function - educational - are engaged in field research and development of innovative research in the agrarian sector. Today, in our country, there is already an experience in defining scientific research and innovation priorities, but until now, the research of domestic scientists did not take into account the use of large-scale modern information capacities to determine the effectiveness of scientific activity. In this regard, the attraction of information technology in combination with the use of international science-computer databases Web of Science and Scopus in the agrarian sphere will significantly expand the scientific outlook of scientists. The aim of the study is to determine the main advantages of using the international science-computer databases Web of Science and Scopus for research in the agrarian sector and to provide suggestions for the search for data and selection of journals for their effective use in the research work of scientific and pedagogical workers of higher agrarian institutions. The information base of the study consists of the current legislation and normative acts of Ukraine, resolutions of the Cabinet of Ministers of Ukraine, official data of the State Statistics Service of Ukraine on scientific and innovative activities, data presented in the international science-computer databases of Web of Science and Scopus. Current issues of the transformation of the scientific system at the state and world levels, which have a positive effect on the level of provision of the research sphere in combination with the staffing component of the scientific and technological potential, remain relevant in modern conditions. Today, we are seeing a deepening of the integration of education and agrarian science within the university sector, which is due to the increasing importance of scientific research and training of agronomists-researchers of the proper level. It has been established that the publication of the results of laboratory-field research in scientific journals indexed in the science science of Web of Science and Scopus should become a promising direction and actively develop among scientific groups of young scientists, in particular, when performing scientific research in agronomy. At the present stage, the development of agrarian production is based not only on the achievements of agricultural sciences such as crop production, agriculture, ecology, fodder production, but also on a number of economic sciences. The studies have taken into account that the importance of research in agrarian science of this interaction is intensified in the conditions of structural transformations of the agricultural economy, as well as the provision of its innovative development, since the integrated interaction of agrarian production, science and agricultural education institutions has a positive effect. In this scientific work, the necessity of the development of science-based research in agrarian universities was determined and the world's bibliometric platforms Web of Science and Scopus were analyzed. It also proved expediency of carrying out scientific researches with the use of science-based studies on the basis of agrarian institutions of higher education. Under the international science and technology databases of Web of Science and Scopus, the criteria and standards necessary for the qualitative use of science in research are researched. Taking into account the results, the main criteria for the selection of science-computer platforms and their indicators were selected: the coverage of Ukrainian scientific publications and publications, the accuracy of data, including the veracity of the citation of the scientific publication, the filtering of excess data, the possibility of obtaining all information about the publication by author. The general characteristics of science-metric databases of Web of Science and Scopus (interface language, data volume, data source, science-metrics) were investigated and the main technical and functional characteristics were determined. Considered the availability of advanced search, the ability to communicate with scientists, the identification of a scientist, the possibility of a reference to a scientific publication. After analyzing specialized literature and sites for the development of international science-computer databases for further thorough research, the course of publications to readers in the Internet space was determined, which is related to the active participation of authors in the placement of scientific articles in such information systems as Google Scholar, ORCID, Research ID. Thus, in agrarian educational institutions, the availability of information and analytical activities in the context of complex changes in the information environment transforms the educational institution into a center of social communication, which is important for conducting research. In this regard, the involvement of information technology in conjunction with the use of international science-computer databases Web of Science and Scopus in the agrarian sphere will significantly expand the scientific outlook of scientists. Information provision of the scientific and educational process at the expense of publications of scientific articles of the corresponding level enhances the role of scientific and pedagogical workers in solving the problems faced by agrarian higher educational institutions at the present stage of development. Therefore, one of the priority directions of activity of scientific and pedagogical workers of agricultural higher educational institutions is the development of navigation functions in the world of science-computer systems in order to facilitate the transformation from the element of research into the participant of scientific and educational work and increase the scientific status of the university.


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