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AZ9RBAYCAN KIMYA JURNALI № 1 2017
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UDC 669.712:669.21
ALUNITE TECHNOLOGY BASED ON HEAP LEACHING
Ch.M.Kashkay, A.A.Gaydarov*, R.B.Kerimov, A.N.Aghaev, Z.R.Jafarov
Institute of Geology and Geophysics, NAS of Azerbaijan *M.Nagiev Institute of Catalysis and Inorganic Chemistry, NAS of Azerbaijan
chkashkay@bk. ru
Received 17.02.2015
This article discusses processing technology of alunite designed by authors by using the heap leaching method and diaphragm electrolysis for the synthesis of base and sulfuric acid. To test the technology in different modes was fabricated a working model. Technology is designed to implement the process directly on the field and has a simple and high profitability.
Keywords: alunite, technology, heap leaching, diaphragm electrolysis, scheme.
Introduction
The processing problem of alunite ores attracted particular attention due to the fact that in Azerbaijan Dashkesan region is one of the world's largest deposits of alunite. Also in the history of technology for the first time in the world in Ganja large plant was constructed for obtaining aluminum from alunite ores, sulfates, sulfuric acid and other products.
It is known that alunite easily soluble in solutions of sodium caustic (potassium) at normal temperature. In this aluminum was transferred to solution as aluminate, and alkali metal sulfates.
Technological aspects of complex processing of alunite discussed in detail in the monographic study of E.Tagiev [1], and in numerous articles and patents of T.Israphilov [2]. Geological issues of alunite detail covered in the two-volume monograph M.Kashkay [3]. Related to alunite physicochemical and thermodynamic processes are described in the monograph Ch.Kashkay [4]. To interested readers can be referred these works.
Unfortunately, many disadvantages of processing technology of Zaylik alunites in due time was caused to stopping Ganja Aluminum plant, which is still idle and the prospects for its start-up is not clear. Partly this might be due to the fact that the restoration of the plant by known techniques requires a large capital cost and plant operation interfaced with relatively high operating costs. Therefor we put the fast working out a new rational and reliable alunit technology.
Description of technology
Our elaboration technology from alunite initiated that grant work about developing technologies for extraction of valuable metals from
iron ores waste in Dashkesan based on sulfuric acid leaching. Calculations showed that the purchase and delivery of the huge amount of sul-furic acid in the Dashkesan can significantly reduce the economic attractiveness of the project. Therefore, it was decided as a source of sulfuric acid use of Dashkesan Zaylik alunite-field, practically adjacent (3 km). In this case goal was set as: to develop the technology of alunite in the most simple and reliable design, with the ability to implement it directly on the deposit Zaylik. To test the technology develop-ped by the authors was designed and constructed a working model of the technological process, on which can be easily checked and adjusted the various technological methods. The model can run in automatic mode at any given speed from alunite heap irrigation and negotiable solutions through the use of controlled peristaltic pumps.
In this model implemented 4 simple processing unit.
1 - Diaphragm electrolysis of potassium (sodium) sulfate for the synthesis of potassium (sodium) hydroxide at the cathode and sulfuric acid at the anode:
(K,Na)2SO4 electrolysis > (-)(K,Na)OH (+)H2SO4.
2 - Leaching of alunite from alunite ore using synthesized alkali (circulating solution):
(K,Na)Al3(SO4)-(OH)6+ 6(K,Na)OH ^ 3(K,Na)AlO- + + 2(K,Na)-SO4~+ 6H2O.
3 - Neutralization aluminate solution by using synthesized sulfuric acid:
2(K,Na)AlO2 2Al(OH)3.
+ H2SO4 + 2H,O
>(K,Na)9SO4
+
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ALUNITE TECHNOLOGY BASED ON HEAP LEACHING
4 - Separation on the filter aluminum hydroxide from the solution of alkali sulfate. The last supplied to the electrolyzer.
The main feature of this scheme is to use the principle of heap leaching, which is widely used in the mining industry for the leaching of various metals. The authors acquired sufficient experience in heap leaching on the Gedabek
mining enterprise. There are different available percolation devices (designed by the authors) for modeling leaching process as a laboratory and pilot scale and even natural.
Offered technology of heap leaching process and indicated technological blocks are shown in scheme (Figure).
Schematic diagram of alunite processing with heap leaching technology.
Some of the technological parameters of the current model
Handmade flow diaphragm electrolizer
consists of a long body chamber. On one body wall was installed along the length of the cathode from stainless steel sheet 200 cm2, and on opposite sides of a sheet of lead anode with a passivated surface with the same area. The distance between the electrodes is 8 cm. The space between the electrodes is divided in the middle of the diaphragm of asbestos sheet. Constant voltage between the electrodes can be varied from 0 to 12 volts. For a flow speed of potassium sulfate (0.1 N) 0.25 //min have been found an optimal voltage 6 V and a current of 3 A. Control is as follows: when feeding the input of the cell potassium sulfate with a neutral pH value, the output in the cathode space pH of the solution should be as high as pH 12-13, and the pH in the anode space of sulfuric acid should be decrease to 2-2.5, which approximates 1N concentration. Provided to these final parameters
can set the desired flow rate and accordingly to choose the voltage on the electrodes.
For industrial production should pick up a ready membrane (diaphragm) electrolizer with the specified performance.
Heap of alunite ore. In this case for the operation of the working model installation was used a small amount of alunite ore (8 kg), which is very roughly simulated heap. For the experiments, a sample of ore containing 30% alunite and grading in the range of 1-5 mm. Used alunite leaching process in our example, as would be expected on the basis of numerous public-cations, flows quite active. Percolation alkaline solution followed by a decrease in pH and temperature. Even at a relatively rapid percolation speed per unit volume of the liquid, we have an equal degree of leaching of 1-3%, and when multiple stream can achieve a output of 80% at room temperature. When more durable washing heap leaching increases to nearly 95%.
In practice, a heap leaching formed according to well-known standards adopted in the
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mining industry [5]. Also known methods of modeling the processes heap leaching.
For finishing the proposed technology to practical implementation, given a predetermined production volume requires additional experiments with percolator and model heaps which can be made available initially using laboratory techniques, followed by a test with the a semi-industrial heap on the Ganja aluminum plant.
The advantages of the proposed
technology
- Eliminates the need of carriage to Dash-kesen Ganja aluminum plant of a huge mass of alunite ore (along with future waste). There is no need to use cableway and rail transport.
- No need for purchased reagents or other materials. For chemical reactions used only alunite components. The use of the diaphragm electrolysis allows from the alkali sulfate to synthesize reagents needed to the process - (K,Na)OH and H2SO4. Received alkali directed to further dissolution alunite and acid partially neutralize the aluminate solution and obtain aluminum hydroxide, and the rest for extracting cobalt, copper and manganese from Dashkesen waste.
- No heating leach alunite, besides cost, dramatically reduces the solubility of silicon in the alkali.
- High profitability can handle alunite ore with condition less than 30% (against 50% at plant technology to ensure the profitability of the plant), which allows more efficient use of reserves.
- It eliminates the problem of utilization of sulfuric acid, which can be used for the tre-
atment of iron waste, and you may receive gypsum from marble chips and dust produced side by side on Dashkesan marble quarry.
- White flakes of aluminum hydroxide, being in the water in suspension, can be easily transported from Dashkesen to the Ganja aluminum plant by the special pipeline by gravity.
So the proposed technology of alunite ore directly from the field, using the technology of heap leaching and diaphragm (membrane) electrolizer, in its simplicity and cost-effectiveness compares favorably with other bulky plant technologies. In addition, given technology, in addition to the production of aluminum, will contribute to the production of a number of valuable metals from nearby masses and deposits of Dashkesan ore unit.
This work was supported by the Science Development Foundation under the President of Azerbaijan Republic - Grant № EiF / MQM / Sanaye-2014-4 (19)-06/06/2.
References
1. Тагиев Э.И. Технология комплексной безотходной переработки алунитовых руд. Баку: Элм, 2006. 503 с.
2. Мамедов М.М., Исрафилов Т.Д., Кязимов Р.А. Способ переработки алунитов. A.c. СССР № 000070. 1993.
3. Кашкай М.А. Алуниты, их генезис и использование. М.: Недра, 1970. Т. 1. 400 c.
4. Кашкай Ч.М. Группа алунита и его структурных налогов. Баку: Элм, 1977. 157 с.
5. Alan Taylor, ALT A Metallurgical Services, Australia. 2016. Key factors for successful heap leaching of gold. http://www.altamet.com.au.
TOPA A§INDIRMA ÜSULU ÍLO ALUNÍTÍN EMAL TEXNOLOGÍYASI
Ç.M.Kaçkay, A.0.Heydarov, RB.Karimov, O.N.Agayev, Z.R.Cafarov
Müalliflar tarafindan hazirlanmiç topa açindirma va diafraqamali elektroliz metodikasindan istifada etmakla qalavi va sulfat turçusunun sintezini hay ata keçiran alunitin emal texnologiyasi haqqinda malumat verilir. Müxtalif rejimlarda texnologiyanin sinaq tacrübalari ûçûn içlayan maketi hazirlanmiçdir. Hayata keçmasi birbaça yataqda reallaçan, sadaliyi va yüksak rentabelliyi ila farqlanan texnologiya taklif olunur.
Açar sozlar: alunit, texnologiya, topa açmdirma, diafraqmali elektroliz, prinsipial sxema.
ТЕХНОЛОГИЯ ПЕРЕРАБОТКИ АЛУНИТА НА ОСНОВЕ КУЧНОГО ВЫЩЕЛАЧИВАНИЯ
Ч.М.Кашкай, А.А.Гейдаров, Р.Б.Керимов, А.Н.Агаев, З.Р.Джафаров
Рассматривается разработанная авторами технология переработки алунита с использованием методов кучного выщелачивания и диафрагменного электролиза для синтеза щелочи и серной кислоты. Для испытания технологии при различных режимах изготовлен действующий макет. Технология предназначена для реализации процесса непосредственно на месторождении и отличается простотой и высокой рентабельностью.
Ключевые слова: алунит, технология, кучное выщелачивание, диафрагменный электролиз, принципиальная схема.
