Superphosphate Production Research Articles

STUDY OF THE MASS TRANSFER PROCESS IN THE WET TREATMENT OF WASTE GASES GENERATED IN THE PRODUCTION OF SUPERPHOSPHATE

In the article, the method of calculation of the process of purification of waste gases generated in the production of superphosphate in a wet method in a rotor-filter experimental apparatus is given. Also, the results of the experiment on the absorption of hydrogen-fluoride gas contained in waste gas into the solution of technical soda in water are given, and the equation for calculating the mass transfer coefficient is recommended. Theoretical and experimental studies mainly selected the optimal values of variable factors.

Partial replacement of rock phosphate by sewage sludge ash for the production of superphosphate fertilizers

AbstractThermal utilization of sewage sludge through mono‐incineration or gasification results in phosphorus (P) rich sewage sludge ash (SSA) that must be returned to agricultural production systems to fulfill the need for recycling of P resources contained in wastewater streams. As the plant‐availability of P contained in SSA is low, we propose feeding SSA directly into the production of superphosphate fertilizers, thereby opening a further pathway for the recycling of phosphorus (P) from wastewater streams to agricultural production systems by using available technologies. We carried out laboratory‐scale production of superphosphate test‐products, in which rock phosphate (RP) was partially replaced with SSA (gasification) before digestion with concentrated sulfuric acid, and evaluated these products with regard to the solubility of P in H2O and neutral ammoniumcitrate solution. We further carried out a growth‐chamber experiment (28 d) using maize (Zea mays L. cv. Sulano) as a model plant on a low P (0.4 mg PCAL 100g−1), high pH (7.6) substrate to evaluate plant P availability of the test products. Our laboratory‐scale results show that at least 8% of P from RP can be replaced by P from SSA while maintaining both the high solubility of P in the fertilizer product and the growth of maize compared to pure RP digested with concentrated sulfuric acid. Further substitution of RP through SSA decreased the total P concentration of the test products, as well as the relative amounts of P soluble in H2O and neutral ammoniumcitrate solution, which affected early plant development of maize.

Preliminary Study of a Method for Obtaining Brown Coal and Biochar Based Granular Compound Fertilizer

A purpose of the research was to develop a method for the preparation of novel organo-mineral fertilizers with the use of brown coal and biochars as organic additives. Brown coal was blended simultaneously together with inorganic materials used for the process of urea superphosphate production in a laboratory scale using a pan granulator and in larger scale using a rapid mixer granulator. Biochars were used for the coating purposes of the urea superphosphate granules on a laboratory scale using a pan granulator. Moreover, the aim was to measure and evaluate the physico-chemical properties of organic materials and the obtained organo-mineral fertilizer products and to study the effects of these products on the selected yield components of spring wheat such as grain yield per plant, spike number per plant, and plant height, in pot trials. Results showed that brown coal and biochars can be used as raw materials for production of fertilizer products. Brown coal contained about 50% of total humic acids while biochar contained nearly 6% of total humic-like substances. Brown coal based compound fertilizer granules produced in the large scale were characterized by particle hardness from 15.80 to 23.3 N while those produced in the laboratory scale were classified as “soft” (particle hardness below 2.3 N). The application of brown coal based fertilizers and two studied biochar coated fertilizers had a positive impact on the grain yield per plant of spring wheat.

Исследование кинетических закономерностей в процессе использования микроэлементосодержащей вулканитовой золы при производстве суперфосфата

Исследование кинетических закономерностей в процессе использования микроэлементосодержащей вулканитовой золы при производстве суперфосфата

Influence of granulating factor at variable humidity on granulation of partially acidulated phosphate rocks

Unstable situation on fertilizer raw material market emerges the need to find substitute for superphosphate fertilizers. PAPR-type phosphate fertilizers (partially acidulated phosphate rock) constitute the most relevant alternative. PAPR-type fertilizers are formed by reaction of phosphate rock with nonstoichiometric, in relation to reaction during superphosphate production process, portion of mineral acid. The resulting product contains an available (soluble in water and/or in neutral ammonium citrate) and less available (soluble in mineral acids) forms of phosphorus. Possibility of using low-grade phosphate rock represents a great advantage of PAPR-type over superphosphatic manufacturing process, where applying phosphate rock of high P2O5 at low impurities content is highly recommended. Granulation process is an essential stage of PAPR-type fertilizers production. Granulation significantly reduces the dust emissions during the fertilizers application furthermore limits the regression of fertilizers in soil to unavailable forms (so-called the aging processes of fertilizers). Optimization of process parameters is very important for economic and ecological reasons because this process is one of the most energy consuming in whole cycle of PAPR-type fertilizers production. PAPR-type fertilizer preparations obtained under laboratory conditions were subjected to examinations. Products were characterized by a variable humidity, which was achieved by altering the concentration of mineral acid used for investigations. The second variable factor was the type of liquid used for granulation. Both, the sieve analysis and determination of resistance were carried out for classification of obtained granules.

Suscetibilidade do capim-colonião e de cultivares de milho ao flúor

A emissão de fluoretos à atmosfera oriunda da produção de superfosfatos e de cerâmica tem causado preocupação pelo efeito tóxico às plantas, contudo são poucos os estudos desenvolvidos acerca do problema com espécie de interesse econômico agrícola. Desenvolveu-se o estudo para avaliar o efeito do flúor (F) atmosférico em plantas de capim-colonião e de cultivares de milho, utilizando como referência espécies bioindicadoras do tipo sensível e tolerante. As plantas foram expostas à contaminação pelo F atmosférico por curtos períodos durante 32 dias em sistema de nebulização com 0,16 mol L-1 de ácido fluorídrico no ambiente interno de uma câmara (~0,20 mmol m-3 de F), havendo um controle não exposto, com quatro repetições. A exposição das plantas ao F causou aumento da concentração do elemento nas folhas até 60 mg kg-1 para o capim-colonião, e entre 100 mg kg-1 nas folhas novas e 170 mg kg-1 nas folhas velhas para quatro cultivares de milho, o que demonstrou o efeito cumulativo do elemento no ambiente. Sintomas visuais da toxicidade foram observados nas plantas e se caracterizaram pela ocorrência de cloroses e necroses na lâmina foliar. O capim-colonião é uma espécie bastante sensível ao poluente no ar. As cultivares de milho DKB 390 e Ômega 8315 também são mais sensíveis ao F quando comparadas às AG7088 e 2B707. Os teores de clorofila a nas plantas foram mais afetados pelo F em relação aos teores de clorofila b.

Mercury Contamination of Soil as the Result of Long-Term Phosphate Fertilizer Production

This study was aimed at determining the range and spatial distribution of mercury in a geographical area influenced by the emissions of phosphate fertilizers industries in Rio Grande, Brazil. The case study demonstrated that mercury concentrations in a fine fraction of the surface soil close to the fertilizer factory reached levels as high as 800 microg kg(-1). Increased mercury concentrations were detected up to 60 cm below the soil surface. Further, a significant impact of the elevated mercury levels was manifested in a 1-km zone around the factory. Technical grade sulfuric acid employed in superphosphate production is considered the principal source of this mercury contamination.

Application of life cycle assessment to the LCA case studies single superphosphate production

There is a competition between wet and thermal routes for phosphate fertilizers manufacture. In the Brazilian case, the thermal route is represented by thermophosphate. This fertilizer is considered the most adequate one for Brazilian agricultural conditions; its main restriction is the intensive consumption of energy necessary for its production. The wet route uses sulfuric acid to direcdy produce the single superphosphate (SSP) or the intermediate phosphoric acid, which will be used to result in triple superphosphate (TSP) and ammonium phosphate production. The main restriction of the wet route is the large amount of phosphogypsum generated in phosphoric acid production. Envisaged is an environmental comparison of both routes using LCA methodology. This paper presents the LCA for SSP production. The goal of the study is to establish the Environmental Profile of this fertilizer. Eight impact categories were selected for the study. The system boundaries was defined for a ‘cradle to gate’ approach, including extraction of natural resources, intermediate products, and production. The SSP system (single superphosphate) comprises the stages of mining and concentration of the phosphate rock, elemental sulfur extraction, production of sulfuric acid, and manufacture of single superphosphate. The LCI was performed considering the production of 1.0 ton of SSP (single superphosphate) as a Functional Unit. The data collected were developed for different producing companies, all of them located in the same regional area. Allocation criteria of energy and mass were applied to the production of sulfuric acid and manufacture of single superphosphate. The transportation step included either the transport of the mined phosphated rock to the concentration plant or the transport of the phosphate concentrate to the SSP unit. The accomplishment of an LCA to SSP production identified the GWP and EP as its meaningful environmental impacts. In reference to global warming, the transportation step was the greatest contributor agent, while the losses of POb4-from the SSP manufacturing were the main cause of EP. The most important contribution in terms of water consumption was observed in the concentration step. Finally, the self sufficiency of the sulfuric acid production in energetic terms must be highlighted. The knowledge of the environmental profile of fertilizers is necessary to support LCA studies of agricultural products, a relevant raw material source for many industrial sectors. The method used here may be important for modelling other LCA fertilizer studies. As most of the agricultural raw materials are transferred among different countries, comparisons of the environmental profiles of fertilizers in developed and developing countries are needed.

A study of chemical interactions in the manufacture of hydrofluoric acid by high-temperature hydrolysis

High-temperature hydrolysis and chemical thermolysis are rather promising methods for processing fluorine-containing products. Research carried out has shown the viability of manufacturing hydrofluoric acid by a non-acid thermal method from refractory fluorite ores and ammonium fluoride-bifluoride, by-products of single superphosphate production. Thermodynamic analysis and laboratory research on ammonium fluoride-bifluoride incineration have made it possible to determine the process temperature of ca. 1000 °C, as well as to select the construction material needed. Tests in a tunnel kiln with fluid feeding of the material and disintegration in hot air (150–200 °C) have confirmed the effective composition of ammonium fluoride-bifluoride. A solution containing over 160 g/l total fluorine and a F tot/NH 3 ratio ca. 30 was obtained under conditions of insufficiency of air required to burn ammonia. With a complete ammonia burn-up as well as use of oxygen blasting, the performance would be considerably improved. Tests on high-temperature processing of fluorite-topaz ores have shown the feasibility of such methods, the specific capacity being 1.25–2.00 t/m 3 with a heat release rate of 6–7 MW/m 3. When the air blast was enriched with oxygen to 30%, the defluorination degree of the material reached 75–90%, the hydrogen fluoride content in the condensate being 120–140 g/l. An additional countercurrent absorption could result in a 35% increase of hydrofluoric acid.

Evaluation of systematic exploitation of tolerance with respect to a declared nutrient content in the production of fertilizers

A given tolerance value on the declared nutrient content of fertilizers is permitted by some national laws. A statistical method to assess systematic exploitation of tolerance values by single nutrient fertilizer producers is proposed. Production of superphosphate was selected as the case study. The method was tested on a yearly production, on randomly selected samples, and on a generated series of samples; it was found to be simple and reliable. The method is theoretically expected to be more reliable than the Wilcoxon test recommended by French law for normal distributions; it appears to fit better than the Wilcoxon test to uneven production of fertilizers.

Efeito da aplicação de efluente da fábrica de celulose junto com fosfogesso na correção da acidez do solo

Foram coletados vários efluentes alcalinos da fábrica de celulose a fim de estudar a utilização destes junto com fosfogesso na correção da acidez do solo. Avaliou-se o poder de neutralização dos efluentes e a lixiviação de sódio na presença de fosfogesso numa coluna de terra. A aplicação do efluente eleva o pH do solo e o volume de efluente necessário para atingir pH 6,5 depende da sua composição química e o poder tampão de acidez do solo. A lixiviação de sódio é maior quando o fosfogesso é incorporado ao solo. A combinação do efluente com o fosfogesso corrige a acidez do solo, aumenta o teor de cálcio e, ao mesmo tempo, reduz o acúmulo de sódio no solo.

Radiotracer investigation of the pulp flow characteristics in the superphosphate production chamber

By means of radiotracer51Cr impregnated in the solid phase the residence time distribution of the pulp in the mixing chamber was obtained. The mathematical model constructed on the basis of the experimental distribution showed an unsatisfactory functioning of the reactor. Ways were proposed to correct this shortcoming, both in the existing chamber and in that which is being designed for a new plant.

Availability of Rock Phosphate as Measured by an Acid Tolerant Pasture Grass and Extractable Phosphorus1

AbstractAs agricultural development intensifies in tropical countries and as costs of superphosphate production increase, the need for further evaluation of rock phosphates has become apparent. An acid tolerant pasture grass (Brachiaria decumbens Stapf.) was used to evaluate the initial and residual (3 years) availability of P from several phosphate materials. A field study was conducted on a Typic Haplustox of the Cerrado of Central Brazil. Initial availability of P supplied as normal superphosphate, Hyperphosphate, Thermalphosphate, and North Carolina rock phosphate was similar when the soils were not limed (pH = 4.3, Al = 1.4 meq/100g). Where lime had been added and pH was increased to 5.4 the P in Hyperphosphate and N.C. rock phosphate was initially less available than P added as superphosphate and Thermalphosphate. After 10 months of contact, lime no longer significantly depressed P availability in these relatively soluble rock phosphates as measured by forage dry weight. The P in the other phosphate rock of low citric acid solubility, Araxá, was virtually unavailable during the 3 months after application. However, within 13 months, maximum forage yields were attained where this material had been applied to unlimed soil and at 25 months maximum yields were obtained on both limed and unlimed soil. Higher rates of Araxá material were required to obtain maximum yields than with normal superphosphate. Forage yields were 2 to 4 times greater where superphosphate was surface applied each year than where similar amounts were incorporated prior to planting. A comparison of extractant methods for soil P indicated that highly acidic extractants (e.g., 0.05 N HC1 + 0.025 N H2SO4) overestimated available P where rock phosphate had been applied. Where superphosphate or rock phosphate had been applied, P availability was better assessed by extractants such as 0.5 M NaHCO3 and Bray 1. The results emphasize the need to supplement laboratory and short‐term studies with long‐term evaluations of P materials with acid tolerant perennial crop species available in tropical countries.

The relative value of water-soluble and ammonium-citrate-soluble phosphorus for wheat production

Wheat production in Australia relies heavily on superphosphate to maintain maximum grain yields. The current rock-phosphate supplies for superphosphate manufacture are derived from Nauru and Christmas Island in the Pacific Ocean; these supplies are anticipated to last only for the next 10–20 years. The supplies of ‘A’ grade ore (apatite) which can be used directly for superphosphate production are greatly overshadowed by large amounts of lower grade rock phosphate which is high in total phosphate but low in apatite. This material is termed ‘C’ grade rock and, to date, it has found little use in Australian agriculture.

Calcined rock phosphate as fertilizer for pasture and cereal production in Western Australia

Calcined rock phosphate is prepared by low temperature (500�F) calcination of 'C' grade Christmas Island rock phosphate that is unsuitable for superphosphate production. It was compared with superphosphate and with mixtures of superphosphate and calcined rock phosphate for pasture and cereal production at two sites in the 12-18 in. annual rainfall zone of the Western Australian wheat belt. At equivalent levels of applied phosphorus, superphosphate was a better fertilizer than calcined rock phosphate over the two years of the trials. There was evidence that the phosphorus in superphosphate was less available when mixtures of superphosphate and calcined rock phosphate were applied, than when superphosphate was applied alone. A pasture response to sulphur occurred at Chapman Research Station on a red-brown sandy loam. There was no response to sulphur by cereals.

Superphosphate production: The influence of various factors on the speed of reaction and the composition of the product

AbstractThe effects of acid concentration, acid/rock ratio, and fineness of grinding on the interaction between Moroccan phosphate rock and sulphuric acid, in the preparation of superphosphate, have been studied.An organic‐solvent technique has been used to follow the course and the rate of the chemical reactions. This method has been adopted because the precise composition of the superphosphate cannot be found by the analysis of water extracts, since interaction occurs between unchanged phosphate rock and free acids during the extraction.Results are given in the form of Tables and graphs.

Business and Finance: February Superphosphate Production About the Same as January.

Business and Finance: February Superphosphate Production About the Same as January.