Разработка технологии азотнокислотного обогащения фосфоритов центральных Кызылкумов с участием этанола

Аннотация

Actually and relevance of the subject of dissertation. Rational application of mineral fertilizer is the main factor for growing high and qualitative yield of agriculture plant. Therefore, optimal prevention of agriculture by mineral fertilizer is one of the topicality issues. The chemical industry in the country after independence, modernization, technical and technological renovation, special attention is given to provide it with a strong base, in particular, by the government on the development of phosphate raw material reserves and local Jeroen-Sardara field step-by-step commissioning program in exploitation. As a result, Kyzylkum phosphorite complex with annual production capacity of 400 thousand tons of products was invaded to reduce import of the raw materials and after implementation of second stage with annual capacity of 716 thousand tons of phosphate concentrate can be stopped complete buy of this product form abroad. At present, the world the special attention is given to the development of new methods of low-grade benefication, in research carried out in this regard, nitric acid and organic solvents on the basis of high-quality phosphate concentrate production technology is one of the most important tasks. When development low-grade phosphorite benefication by nitric acid in presence of organic solvents, should be based a number, including relevant scientific solutions in the following areas: development of effective ways of chemical benefication of raw phosphate; finding optimal condition process of leaching calcium nitrate, formed during the benefication of high calcareous phosphorite by nitric acid in presence of organic solvents; development of phosphoric fertilizer technology based on quality chemical benefication of phosphorite concentrate. Thesis topic is explained by the implementation of the scientific research in this area. This dissertation research is to a certain extent the tasks provided for in the decree, and decrees of the President of the Republic of Uzbekistan No PD-4707 on March 4, 2015 «On programme for measures of structural reforms, modernization and diversification of production in 2015-2019» and the resolution of the Cabinet of Ministers No 8 on January 22, 2015 «On additional measures to reduce production costs and reduce production prime cost in the industry», as well as other regulatory legal instruments adopted in this area. The research objective is study Kyzylkum phosphorite enrichment by nitric acid in the presence of ethanol, followed by the processing of phosphorite concentrate in phosphorus compound fertilizers and calcium nitrate in the liquid and solid nitrogen-calcium nitrate. The scientific novelty of the thesis research is as follows: for the first time there have been obtained the new data on the chemical enrichment of the CK phosphorite with nitric acid followed by leaching of the resulting calcium nitrate by ethanol solution, depending on the norm of acid and the ratio of phosphorite to ethanol; it has been established that ammoniation of nitrogen-calcium-phosphate slurry to pH = 3 that allows to completely prevent the loss of P2O5 in the liquid phase; solubility diagram studied 4 fourfold component system of Ca(NO3)2 -NH4NO3 - C2H5OH - H2O, consisting of 3 triple: Ca(NO3)2 - C2H5OH - H2O; NH4NO3 - C2H5OH - H2O; Ca(NO3)2 - NH4NO3 - H2O and 3 triple binary systems of Ca(NO3)2 - H2O; NH4NO3 - H2O and C2H5OH - H2O, result in which minimum amount of ethanol were defined, depending on the technological parameters of the nitric acid benefication of carbonate containing phosphorite;there have been defined the physicochemical properties nitrogen-ammonium-calcium solution and in case the addition of bentonite to the solution can be obtained a granulated calcium nitrate with improved properties; there been found the optimum conditions of the conversion of calcium nitrate that is a by-product of the nitric acid benefication of CK phosphorite in NH4NO3 and CaCO3 using CO2 and NH3; there been developed the technology for processing of chemically enriched phosphoconcentrate in WPA, PK- and NPK-fertilizer. CONCLUSION 1. Solubility diagram 4 fourfold component system of Ca(NO3)2 - NH4NO3 -C2H5OH - H2O has been studied, consisting of 3-triple: Ca(NO3)2 - C2H5OH - H2O; NH4NO3 - C2H5OH - H2O; Ca(NO3)2 - NH4NO3 - H2O and 3 triple binary systems of Ca(NO3)2 - H2O; NH4NO3 - H2O and C2H5OH - H2O, justifying the process of extraction of calcium nitrate and ammonium nitrate from nitrogen-calcium-phosphate slurry produced during nitric acid enrichment of phosphorite CK by ethanol in a wide temperature and concentration range. Diagram allows to define the range of variation of technological parameters of the extraction process based on CaO: P2O5 phosphate raw materials and the conditions of its nitric acid decomposition. 2. The process of enrichment of various kinds of carbonate phosphorite from CK in HNO3 at a norm of 30 to 60% of the stoichiometry on the decomposition of CaO in the raw material and a weight ratio of PR: EA = 1: (3-10). The overall picture of the results of enrichment of different types of phosphate rock in HNO3 is similar. Thus, the enrichment of relatively high concentrated OPF with the content (wt.%) P2O5 18.70; CaO 47.8; CO2 15.3; SO3 2.05 and CaO: P2O5 = 2.56 at a norm of HNO3 is 40% on the decomposition of CaO (100% for CaCO3) and the ratio of PR: EA = 1: 5 is obtained phosphorite concentrate containing 26.19% of P2O5, and calcium module 1.52. This concentrate is quite suitable for the production of concentrated phosphate fertilizers. To prevent the transition of P2O5 into a liquid phase before divide nitrogen-calcium-phosphate alcoholic suspension (NCPAS) into liquid and solid phases, it was ammoniated to pH = 3. This made possibility to use for enrichment much higher norm of HNO3 and thus reduce the value of CaO: P2O5 in the raw material. Norm acid is ranged from 40-80% stoichiometry for CaO in the raw material. Taking into account the cost savings of HNO3 its optimal norm for the enrichment of various types of Kyzylkum phosphorite can be considered 50% and the weight ratio of PR: EA =1:5. And for MM acceptable norm is of 60%. So, when RPF enrichment, containing 17.52% of P2O5; 47.53% of CaO; 15.23% of CO2 and CaO: P2O5 = 2.71 with a 50% norm of HNO3, pH of the slurry and the ratio of PR 3: EA =1:5 obtained concentrate composition (wt.%): P2O5tot. - 26.20; CaOtot. -38.25; CO2 - 2.80; CaO: P2O5 = 1.46. The yield of P2O5 in the concentrate is 100%. 3. The theoretical analysis of the regeneration of the NACS with the use of solubility diagrams of 4 fourfold component system of Ca(NO3)2 - NH4NO3 -C2H5OH - H2O, the result it was calculated alcohol recovery process and determined the interval of variation of process parameters, taking into account the composition of the starting water-alcohol solutions and final products. The kinetics of the distillation EA from NACS depending on the temperature and pressure has been studied. Applying a vacuum pressure of 0.3 atm. provides EA distillation for a short time (60 minutes at 80°C). When the regeneration EA from calcium nitrate solution, which is a by-product of the nitric acid concentration of CK phosphorite, degree EA return to the cycle reaches 98-99%. After distilling off the NACS has been obtained containing 50% Ca(NO3)2 and 3% NH4NO3. 4. Physicochemical properties of the initial and productional NACS depending on the concentration of Ca(NO3)2 and NH4NO3. It is shown that in the concentration range of 53.02-65.71% of NACS the crystallization temperature is in the range of (-75) + 12.0°C that allows to be used them in the spring and summer, as a liquid nitrogen-calcium fertilizer. NACS has good rheological properties. However, more concentrated NACS (67.83-84.77% of Ca(NO3)2, 3.83-4.77% of NH4NO3) before use should be diluted with water, as the crystallization temperature is 29-60°C. It was found that with increasing concentration NACS increases its the boiling point. NACS was processed in granular calcium nitrate. To improve the properties of the latter various bentonite clay deposits are used as additives. The products obtained with a ratio of Ca(NO3)2: Betonies = 100 : 6 nitrogen content is in a range of 14.49-14.69%. Physical and chemical properties of the resulting products have been defined. Optimal conditions for the conversion of calcium nitrate of NACS in NH4NO3 and CaCO3 using ammonium carbonate. Based on the results of studies recommended the following conditions conducting the conversion process: concentration of calcium nitrate solution is 37%, the norm of ammonium carbonate is 120% of the stoichiometry, conversion of temperature is 70°C, mixing time is 120 minutes. The degree of conversion of calcium nitrate is maximum 99.94%, and the concentration of ammonium nitrate solution is 45%. 5. Developed technology of Kyzylkum phosphorite enrichment by nitric acid in presence of ethanol has been tested in the model laboratory plant and pilot plant of JSC «Samarkandkimyo» with the output of an experimental batch of chemically enriched phosphoconcentrate. Material balance for enrichment process of phosphorite flour containing 17.52% of P2O5 has been complied. The circuit includes a step of decomposing the raw material by nitric acid repulping nitrogen-calcium-phosphate slurry with circulating alcoholic solution of calcium nitrate, neutralization with ammonia suspension two fold washing wet phosphoconcentrate by circulating calcium nitrate solution, and ethanol, as well as drying the final product. 6. Studies on preparation of WPA from chemically enriched phosphoconcentrate containing 26.2% of P2O5 in the dihydrate mode depending on the norms of H2SO4 103%; the concentration of circulating WPA is 15% P2O5, and the ratio of L: S = 3: 1. In this KeXp. = 98.73%; Kwas. = 98.57%, Kyej. = 92.87%, a filtration rate is 1312 kg / m2 • hour, and the concentration of phosphoric acid is 20.19% of P2O5. Content CaOtot.; SO3lot.; P2O5tot. and P2O5wat. is 31.21; 43.23; 1.43 and 0.27%, respectively in the dried phosphogypsum. Material balance of the process of obtaining one ton of P2O5 in the form of WPA has been estimated. The process obtaining compound-mixed PK- and NPK- fertilizer in a wide range of ratios of nutrients has been studied by mixing wet phosphoconcentrate crystalline potassium chloride and ammonium nitrate. A block diagram of the complex processing of phosphorite of CK by HNO3 has been developed. 7. For the approximate determination of the economic efficiency of the organization of production of chemically enriched phosphoconcentrate made economic calculation productions of WCPC and chemically enriched phosphoconcentrate and ammophos based on them on the basis of processing of one thousand ton of phosphate ore averaged of Kyzylkum. It has been shown that the overall manufacturing cost of one ton of WCPC is 206155 sums and chemically enriched phosphoconcentrate is 149657 sums that 56498 sums cheaper. Thermal enrichment of 1,000 ton of phosphate rock 433.94 ton of WCPC is obtained, and when chemical processing is 668 ton of phosphoconcentrate. Of these, it is made 235.1 and 361.8 ton of ammophos to the amount of 258 255 469 and 397 434 406 sums, respectively. That is additionally produced the product in the amount of 139 million 179 thousand sums.