CC BY
13
50m --
i-^-----
Figure 2. the scheme of cell with impact on layer with alternate current
Table 1.
Maximal depth of treatment, m 150
Tension, kV 50
Volume of impulsive condensator, mkF 0,5
The charge tension, V 220
Consuming power, kVt 1
An essence of the physical effect of sandy-argillaceous ores' promotion while transmission ofelectrical power in department ofloamy fractions associated water, whereupon increases section of pores. Besides, unlike constant current, alternating current impacts on water too that immobilized by helium, mudding pores spaces. Thixotropic (helium like) structure is formed in contact with sulfuric acid and argillaceous fraction of the ore owing to crystallizational cement's solution and their softening. Helium even during negligible quantity of solid material (1-10%) accounts a big volume, that stipulated net structure in cells ofwhich contains 90% and higher immobilized water. Immobilized water differs from water ofdiffusive layer with the first is not connected with cations and not pulled up surface charges of particles.
DOI: http://dx.doi.org/10.20534/ESR-17-3.4-92-94
Atabaev Farrukh Bakhtiyarovich, doctor of philosophy (Ph. D.) in technics, senior scientific research, research and test center «Strom» Institute of General and inorganic chemistry of Academy of Sciences of the Republic of Uzbekistan
E-mail: [email protected].
Waste from flotation enrichment of rocks — as a complex raw material for the cement industry
Abstract: Provides information about the possibility of obtaining an extension of the portlandcement with the use as additives-fillers secondary raw materials: recycled steel slags, waste, flotation of tungsten, and fluorite ores of Uzbekistan, "dry" and "wet" wastes of production of chrysotile-cement products.
Keywords: beneficiation of ores by flotation, secondary raw materials, additive in cement, portland cement additional, physical and chemical properties, structure, hardening, the formation of artificial conglomerate, strength, brand, environment, economy.
Introduction. The trend of development of the cement industry of Uzbekistan is aimed at reducing fuel and energy costs per unit of production and increasing the volume of cement production through maximum involvement in the production process local raw materials of natural and anthropogenic origin, not worsening the quality of cement. To do this, cement plants of the republic carried out a deliberate policy on the adoption of appropriate measures in the field of exploration of promising new sources of local cement raw materials. In this aspect, the most important is the question of finding new sources of mineral admixtures and additives — filling cement, clinker ensure maximum savings component while improving the physical and mechanical, construction and technical properties of the cement additive.
Formulation of the problem. Due to the fact that the flotation tailings tungsten (FTTO) and fluorite ores (FTFO) are alumino-silicate minerals with impurities of different oxides may be used as additives to cement. This requires a comprehensive study their properties in order to determine the possibility of using as an additive in the production of cements with additional optimization of their content in the composition of additional cement and to determine the physical and mechanical properties and compliance with the data requirements of the Interstate standard GOST 10178-85. At the same time, the development and application of technology for additional cement using waste flotation concentrators is not only technically feasible option saving energy and resources in the production of ce-
ment additive, in quality not inferior without additional cement and physico-mechanical properties meet the requirements for cement with mineral additives brand PC 400 D20, but the actual decision of environmental problems.
Materials research methods, equipment and instruments. During the experimental research as the starting materials used are Portland cement clinker ofJSC "Kizilkumcement" and JSC "Akhan-garancement", gypsum, flotation tailings deposit Ingichka tungsten ores and fluorite ores (deposit Agatha — Chibirgata). Investigations were carried out in an accredited laboratory of the Research and Testing Centre "Strom" Institute of General and Inorganic Chemistry of the Academy of Sciences of Uzbekistan, which is equipped with the necessary tools and equipment to perform chemical analysis and physico-chemical and physical-mechanical source of raw materials and cement (analytical laboratory, DTA, IR, X-ray, electron microscope). Determination tails activity enrichment fluorite and tungsten ores in order to establish their application as active mineral or filler additive for Portland cement, carried out by determining their compressive strength and, then by calculation — by Student's test according to the procedure of GOST (State Standard) 25094.
Results and its discussion. Determination of the chemical composition of samples of the flotation tailings fluorite ores showed that its chemical composition is represented mainly by the content of silicon oxide, the presence of calcium oxide, aluminum,
Waste from flotation enrichment of rocks — as a complex raw material for the cement industry
iron, magnesium. The magnitude of mass loss on ignition, as well as the presence of calcium oxide and sulfur trioxide indicates the presence in the samples of the flotation waste carbonate and sulfate compounds (table 1). The composition of the flotation waste secondary enrichment oftungsten ores is characterized by the presence of oxides: silica SiO2; Al2O3 aluminum; Fe2O3 iron; calcium magnesium CaO and MgO. Based on the chemical composition of the forecasted made the conclusion about the possibility of the use of waste as a filler additive for cement production.
It is known that the main criterion for determining the use of a supplement, is an indicator of its activity, defined by its ability
to absorb CaO of saturated lime solution or compressive strength, determined by Student's criterion [1; 2].
As a result of testing and mathematical transformations of the results obtained by the method of GOST 25094 established that the value of the Student test for flotation tailings fluorite ores amounted to t = 4,18, and for the flotation waste secondary enrichment of tungsten ores - t = 4,54, which is greater than he standard value t > 2,07. Consequently, both the flotation considered to pass the test of strength and activity, in accordance with Oz DSt (National Standard of the Republic of Uzbekistan) 901-98 (p. 4.2), they can be used as additives for cements.
Table 1. - The chemical composition of the starting components
Material The content of the mass fraction of oxides,%
LOI SiO2 A1,0, CaO MgO SO, other £
Clinker 0,75 20,54 5,19 3,56 62,04 3,60 0,62 3,7 100,0
Gypsum stone at 400 0 C, 19,10 1,52 0,13 0,14 33,04 0,20 43,46 2,41 100,0
FTTO 4,89 46,17 5,28 14,90 21,71 2,22 Ca. 4,83 100,0
FTFO 2,81 88,89 1,89 1,60 2,90 0,52 1,02 0,37 100,0
For use of a particular type of mineral cement admixture necessary to determine the efficiency of its use in accordance with GOST 25094 and set the optimum dosage of the cement additive. To this end, a study on the optimal dosage of flotation waste tungsten and fluorite ores in the cement and the optimal composition of Portland cement with the addition of these wastes. For this joint grinding of clinker and additives composite sample fluorite flotation tailings and tungsten ores in the presence of 5% gypsum was performed in a
Conclusion. The possibility ofusing up to 15% ofmineral techno-genic waste—flotation tailings tungsten and fluorite ores as an additive filler in the production of common Portland cement without reducing their grade strength. Flotation waste concentrators, according to GOST 24640-91 "Additives for cements. Classification ", by the nature ofthe main effects on the properties ofcement, can be attributed to the components ofthe material composition of cement. The main effect of
laboratory ball mill. The amount of the admixture was (10, 15, 20)% by weight of clinker. As a basis for comparison, a cement composition in which no additives were manufactured by co-grinding of the clinker with 5% gypsum. The results show that the introduction of up to 15% fluorite flotation tailings tungsten ores and does not reduce the strength of cement, comprising an additive which has not (Table 2). The increase of flotation waste reduces the strength of cement on one brand [3-5].
the impact of this type of additive is to save the clinker, and the main criterion for evaluating the properties of the additive — a greater decrease in the proportion of clinker than the decline in the cement activity. The use ofthese additives reduces energy costs for clinker grinding, increase production and reduce the cost of cement and at the expense of large-scale utilization offlotation waste - improving the environmental situation in the areas of mining and enrichment plants.
Table 2. - The test results of additional portlandcement containing flotation tailings fluorite and tungsten ores
Designation of cements Clutch time, hour - minute the expansion cone, mm Tensile strength after 28 days (kgf/cm 2)
Start end flexural Compres-sive Growth (+) or loss (-) strength
Additional cements flotation tailings fluorite ores
PC D 0 2-18 3-34 115 67,0 413 -
PC D10 2-35 3-44 114 65,7 406 +7,0
PC D15 2-48 3-52 115 64,1 403 + 10,0
PC D20 3-10 4-14 114 60,5 376 -27,0
Additional cements flotation tailings tungsten ores
PC D 0 2-15 3-30 114 68,2 402 -
PC D10 2-55 3-40 114 76,1 410 +8,0
PC D15 2-45 3-35 116 75,4 418 + 16,0
PC D20 2-55 4-00 115 59,6 367 -35,0
References:
1. Oz DSt 901-98 "Additives for cements. Active mineral additives and fillers, additives. Technical conditions". Put into action by the order of the State Committee of the Republic of Uzbekistan for Architecture and Construction number 44 on - June 5, - 1998.
2. GOST 25094-94 "Active mineral additives for cement. Test methods". Interstate standards. Put into effect from 1 January - 1996 in -Moscow. G. - 1996.
3. Atabaev F. B. Development of the production technology of portlandcement clinker with use of waste of enrichment of tungsten ores // The Abstracts of the International Porous and Powder Materials Symposium and Exhibition PPM - 2015. - 15-18, September -2015. Cesme Izmir-Turkey. - P. 515-519.
4. Khabirov R. S., Mirhamidova F. Z., Alekhina G. B., Iskandarova M., Atabaev F. B. and others. «Tails» enrichment of tungsten ores -complex raw materials for cement manufacturing // Ecological Bulletin. - No. 4, - 2015, - P. 11-14.
5. Iskandarova M., Atabaev F. B., Myronyuk N. A., Kadyrova F. D. The new technological solution to produce clinker and cement additive with complex use of man-made mineral ingredients//Materials of international scientific practical conference. - Bukhara, 10-12 -November - 2015. - P. 255-258.
DOI: http://dx.doi.org/10.20534/ESR-17-3.4-94-97
Qasimov Huseyn Alakbar oglu, Nakhchivan State University Master, senior lecturer of programming Nakhchivan, Azerbaijan E-mail: [email protected]
Application of Rnd () function in the process of question choice in electronic exams
Abstract: In the article, the advantages of application of RND () function to the algorithm of introducing the questions to the students in the electronic exams. As a result of research, it was known that the application of RND () function to the process of question choice in the electronic exams incites the students to study more. The work implies that as the selection of every question in this process is occasional, full hypothesis of dependence of the meeting level of credits on the subject on the volume of material read has been calculated for all cases, verity of the so-called ideas has been proved theoretically. Besides, the advantages of application of RND () function to the algorithm of introducing the questions to the students in the electronic exams have been proved theoretically and the results of researches carried out over 4000 students were demonstrated practically.
Keywords: electronic University, electronic exam, occasional process, hypothesis, irrelevant occurance, RND.
It is known that major duty of high educational institution is to provide the society with citizens having a high scientific potential. And the rating of Universities is directly related to the achievements gained by the cadres in different fields of industry. That is why universities always search for innovative methods to bring up more educated cadres. The students' evaluation level of assimilating knowledge in the operational process of universities is one of the major conditions. Final assessment of students' assimilating the knowledge had been carried out in the exams before. In this case the students' education level was assessed incorrectly. So that the students who are active in seminars are not able to answer the questions properly in the exam because of psychological tension or vice-versa the students don't demonstrate any activity along the semester who rely on his or her memory and the ability of swotting. Only in the end, he or she could get the adequate mark by cramming up the material temporarily. Consequently, the students can't get success in their activities after becoming graduates and this caused to the emergence of negative ideas about Universities.
However, after 1999-Bolony declaration was accepted and more than 49 countries of the world joined this process, evaluation criteria changed in education as well [1].
Thus, the student's knowledge level is evaluated not only with exam points, but also for his or her daily activity, free work, précis work on the whole. This is, in its turn, a good case that the student is obliged to demonstrate good activity both in semesters and in the exams. But sometimes the students succeed in meeting the credits without full assimilation of teaching materials in this process. The passage to the electronizing the exam process is suggested in order to achieve the assimilation of teaching materials by the students in Bologna process. In this case the students are examined by means of tests. Meanwhile, there is an opportunity to ask the students more questions. As the evaluation performed by the computer, the mark is completely objective. Application of Rnd function in the process of question choice in such kind of exams gives better results. Let's
make comparison between traditional and electronic exams in order to specify all afore-said.
It is known that the student must perform minimum 51% result to have met the credit on the subject. Let's suppose that the student have demonstrated 47% result in semester. In this case his or her scoring the minimum point in the exam is sufficient to have met the credit. This point changes between 17-25 depending on the decision of Ministry of Education of every country.
In traditional exam the questions are prepared by the teacher in the form of tickets beforehand and are hung on the exam poster. As a rule, the tickets cover the questions of the materials had in this or that way. In case the student gets ready for 60% of the tickets perfectly, this time, hypothesis of his or her taking the tickets that he or she studied for the exam equals 0,6. So the hypothesis of student's getting an excellent mark equals 0,6, in other word 60%.
On the contrary, let's suppose that exam questions are not given to the students. If the student studies 60% of the material perfectly again, the student will answer 60% of the questions. And this means that the student will definitely get a satisfactory mark and it is even possible for him or her to get a good mark.
The questions between 500-1000 are prepared in the electronic exam. At this time the teacher who teaches the subject notes which theme it belongs to in relevant section in front ofevery question. While placing the questions in the system, they are arranged in the form of variants separating them to some definite numbers manually (for example, being 50 questions). This way is not so effective. That is why the student can get a grade without studying the material completely.
The most effective way in the choice of questions in the electronic exam is the application of Rnd () function to the algorithm selection.
It is known that Rnd () function is the most effective function generating occasional figures in two-number ambit shown [4].
In case Rnd () function is applied, the algorithm of question selection process can be formed shown as in figure 1.
