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Section 6. Chemistry
Garaybayli Samira Aslan, Azerbaijan State Oil and Industry University Engineer, the Faculty of Chemical Engineering E-mail: syamakerim@gmail.com
Gambarov Mirsalam Beyukaga, Ministry of environment and natural resources
of Azerbaijan Engineer E-mail: bvl_ok@rambler.ru Atayev Matlab Shixbala, Azerbaijan State Oil and Industry University Lecturer, the Faculty of Chemical Engineering E-mail: bvl_ok@rambler.ru
Alosmanov Mirali Seyfaddin, Azerbaijan National Academy of Science Professor, Institute of Geology and Geophysics E-mail: alosmanov1143@scientifictext.ru
DEVELOPMENT OF ECOTECHNOLOGY OF A SLAG PRODUCED FROM MUNICIPAL SOLID WASTES (MSW) INCINERATION BY ADDING MODIFIERS (PHOSPHORITE AND PHOSPHOGYPSUM)
Abstract: In the article of "Working out of ecotechnology of the slag, received by burning of solid municipal wastes by addition of modifications". It has been determined that by addition of phosphorites and phosphogypsum into the slag, the organic complex fertilizer will be received by the following composition: P2O5 assimilated; K2O - 6.4%; CaO - 20.4%; yield of aim product - 94.6%; grains hardness - 1.7 MPa.
Keywords: slag, phosphogypsum, phosphorite, fertilizer.
Introduction. Development of utilization technology of treated macro-, microelement wastes (slag, sludge), and multicomponent modifiers from sorting and incineration of organic mineral complex wastes; different production processes, extraction, transportation, processing, application of minerals is one of the most important problems. Growth of non-oil sector and improvement of ecological situ-
ation for solution of these problems are the main factors. Environmental improvement is closely connected with the use of cheap wastes and non-ore natural mineral compounds. In the entire world, including our country a great amount of slag is formed in metallurgy fields of many industries [1-3].
Our republic is rich with the reserves of cheap macro- and microelement modifying compounds.
Unfortunately, they have not been found their application fields up to now. Development of utilization technology of treated wastes by adding cheap and local natural compounds is the basis for all these. For example, 1500-1800 tons of organic complex mineral wastes (MSW) are formed per day in Baku and its regions. These wastes are incinerated in a plant of Balakhany district in Baku and the resulted bottom ash and flue dust are not used and remain unused around the plant.
Presently, the amount of such wastes in every country is million tons and they accumulate and pollute atmosphere, hydrosphere and lithosphere.
If we consider that despite sufficient reserves of low-quality phosphorite there is no information on the use of it for preparation of phosphoric fertilizer or phosphate in technical literature. But phosphorite has been used as a neutralizer up to now. This is not economically useful for protection of soil reserve. In this study, we have developed ecotech-nology of slag waste using previously unused in this field phosphorite as a modifier with rich reserves in the Republic of Turkey and Nakhichevan AR. According to our goal, we have also used phosphogyp-sum. Phosphogypsum is prepared by the following reaction with the mixture of sulfate and phosphate acids [4].
Ca5F(PO4)3 + 5H2SO4 + nH3PO4 = (n+3) H3PO4 + +5CaSO4 • mH2O + HF
Phosphogypsum, produced in the reaction, always draws attention. When the soil is enriched with phosphogypsum, it actively effects on the formation of soil and improves its chemical composition. It contains calcium (30%), sulphur 23-25%, SiO2 0.3% and microelements. Furthermore, phosphogypsum contains many compounds that are necessary for plants and soil. Considering this, we used phosphogypsum with a certain compound or as a modifier in one of our works [6-8].
It is known that our republic needs 450-550 thousand tons of fertilizer and it is dearly bought from abroad. However, using local reserves we may produce nearly 45-55% of it in our republic.
Our aim is the treatment by using a slag and the following local modifiers formed during incineration of MSW and development of utilization technology. Phosphogypsum and phosphorite were used as a modifier. To achieve our goal we used a slag from the incineration of MSW and modifiers. Presently, only the wastes formed in Baku are burned in Balakhany district. The amount of this waste is av-eragely 1600-1700 tons per day. 250-350 kg slag is produced during the incineration of this waste. Table 1 shows chemical composition of this waste.
Table 1. - Composition of 250-300kg of slag formed averagely during incineration of 1 ton of MSW
Results of anal yses of burned waste,%
Name Na2O MgO Al O SiO2 PA SO3 K2O CaO TiO2 MnO Fe O Cl YTI
Waste burned № 1 (bottom) 5.82 2.42 4.12 14.86 2.12 2.56 2.27 32.47 0.83 0.21 10.31 2.07 19.48
Waste burned № 1 (flue) 2.92 1.26 1.52 6.53 0.94 3.80 7.14 34.62 0.98 0.24 3.90 14.62 21.12
Chemical composition of phosphogypsum used in this research work is given in (table 2). Table 2. - Chemical composition of phosphogypsum
CaO SO3 PO gen P2O5 in water RO 2 3 Fe O 2 3 Al O 2 3 MgO F CO2 dissolution RO 2 3
33.5 47.1 1.1 0.7 0.5 0.2 0.1 0.3 0.3 0.1 16.5 0.1
Low-quality Nakhichevan phosphorite was also used in this work. Its composition is given in table 3 (%
Table 3. - Composition of Nakhchivan phosphorite
CaO P2O5 SO3 F CO2 K2O MgO Mn Fe O 2 3 AlO. 23 TiO2 Organic comp. HgO Other mixture
39.5 14.4 0.15 2.1 2.2 1.5 3.8 1.6 2.5 1.01 1.41 1.7 2.71
In laboratorial condition 100 ml of processed H2SO4 is poured into 0.5 l of cylindrical reactor and heated at 35-40°C and 50g of slag (slag is produced from MSW incineration) is added and mixed. After 10-15 minutes 50g of phosphorite is delivered into reactor. The sample is taken from the reactor. If necessary elements in slag and phosphorite pass to the solution 50g of phosphogyp-sum is added into the reactor. Cylindrical reactor is placed in a drier and kept 60-90 minutes at
100-105°C. Then reactor is removed from drier and fertilizer is taken from reactor and neutralized, granulated and dried. The composition of granule complex fertilizer is given below (mass%): P2O5 - adopted 13.5%; K2O - 6.4%; CaO - 20.3%; P2O5 - free 2.4; MgO - 2.5; MnO - 1.3; H2O - 2.2; solidity of a granule 1.6-1.7 mPa, yield of the main product is 94.6%.
Scheme of technological installation of the research work has been developed.
Figure 1. Technological scheme: 1 - tank for H2SO4; 2 - hopper for MSW; 3 - screw; 4 - hopper for modifiers; 5 - granulator; 6 - drier; 7 - elevator; 8 - sieve; 9 - final product line; 10 - recycle line; 11 - grinder
Description of the technological scheme. Processed sulfuric acid is delivered to a tank (1), crumbled slag is delivered to hopper (2). Screw (3) is put into operation firstly. Then slag is delivered to screw from acid tank (1) and slag hopper. Modifiers are delivered onto the compounds in screw. The mixture produced in screw is delivered to granulator (5); then is passed into recycle separated from sieve (8).
Granule mass in granulator (5) is delivered to drier (6). Dried material is passed to elevator (7). Dried product is delivered to sieve (8) via elevator (7). It is divided into three parts there. 0.5-1.0 mm product is delivered to recycle granulator, 1-5 mm final product is delivered to 5 mm grinder (11), and then sent to elevator and process. 10 g of slag contains FeO, Fe2O3 compounds. The amount of phosphorite in 1 g phosphorite is 0.89 g, when both
of them are decomposed in sulphuric acid iron is converted into FeSO, and H PO . Free H,PO„ is
4 34 34
decomposed and P2O5 is produced. As a result the following compound which is used in agriculture is produced. FeSO4-11-17%; P2O5 (free) - 8.511.3%.
Conclusion
In the work on the development of utilization technology of slag formed during incineration of municipal solid waste with local modifiers it was determined that complex fertilizer can be produced by adding low-quality phosphorite and phospho-gypsum into a slag with rich reserves which disrupts ecological balance. Amount of P2O5 adopted in granule complex fertilizer is 13.5%; K2O - 6.4%; CaO -20.3%. The yield of the main product is 94.6%. Solidity of granule is 1.6-1.7 mPa.
References:
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6. Kaniskin M. A., Gorlenko A. S., Terekhova V. A. Estimation of biological activity of soils on emission of carbon dioxide in disposal of phosphogypsum dumps. Materials of II International scientific and practical conference "Soil as interlink for functioning of natural and anthropogenically transformed ecosystems". Irkutsk, 2-7 September, - 2006. - 363 p.
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