The manufacture and evaluation of granular potassium chloride fertilizers

A finely divided red potassium chloride (KCl) (particle size distribution: 79% <0.5 mm, 20% 1-0.5 mm and 1% 1–2 mm) was granulated by adding eight readily available and relatively inexpensive binders using a rotating drum in the laboratory. The binders used were: urea, pulp and paper waste liquor containing lignosulphonate, urea + pulp and paper waste liquor, Borrebond powder (a commercial product containing lignosulphonate), urea + formaldehyde, ammonium sulphate, ammonium sulphate + pulp and paper waste liquor and a waste liquor containing ammonium sulphate from a Ferritin production plant. Of these, except for urea and urea + pulp and paper waste liquor which produced KCl granules having low critical relative humidity at 30°C (CRH) (<55%) and Borrebond which produced KCl granules of low crushing strength (1.1 kg for 2–3 mm granules) the other five binders produced granules with good size distributions, high crushing strengths (2.0–2.5 kg for 2–3 mm granules), CRH (65–70%) and suitable nutrient contents (K, 46–50%, Cl, 42–47%). These values are very close to those of the standard chipped KCl (crushing strength, 2.5 kg; CRH, 65–70%; K, 50%; Cl, 47%).Crushed chipped KCl (74% <1 mm, 25% 1–2 mm, 1% 2–3 mm) when cogranulated in the pilot plant with the 5 binders found successful in the laboratory, produced granules having similar characteristics as the corresponding ones produced in the laboratory. Granules produced both in the laboratory and the pilot plant had lower abrasion resistance (higher % degradation) than chipped KCl. The abrasion resistance however markedly increased when the fines (<1.4 mm) in the granules were removed.Glasshouse trials using barley as test crop demonstrated that the agronomic values of the KCl prototype granules produced with the 5 binders were similar to chipped KCl and granules produced from the feedstock KCl and water.     

Some technological laws and properties for highly porous ceramic concretes

Conclusions Using ceramic concrete made from zirconia as an example we formulated conditions and established the main technological laws for obtaining highly porous ceramic concretes.We analyzed the composition and microstructure of the ceramic concrete from the point of view of the existence in the system of noncompensated shrinkage. It is shown that for ceramic concrete with a high bond shrinkage during drying and heat treatment, with the purpose of reducing the shrinkage stresses in the system, it is necessary to use multifraction (coarse, medium, and fine) fillers.We show the effectiveness of using, as one of the filler components, removable poreforming additive, based on foamed polystyrol.The optimum region of the grain-size distribution of the components was established; this comes within the true specific volumes in the structure of the shaped ceramic concrete and amounts to 20–30% bond, 20–25% fine (0.1–0.4 mm) and 25–40% coarse (5–10 mm) filler made from waste zirconia foamed ceramics, and 20–25% foamed polystrol (0.63–1.6 mm).We studied certain properties of the resulting materials with a porosity of 60–75% and a compressive strength of 5–20 MPa.Compared with other highly porous materials, for example, foamed ceramics, the highly porous ceramic concretes have technological advantages (much lower water capacity of the shaping system, reduced shrinkage in drying and firing) and also improved operating characteristics, for instance, thermal conductivity, thermal-shock resistance and volume constancy.Translated from Ogneupory, No. 2, pp. 20–25, February, 1984.     

Vibratory densification of thermal insulation corundum products

Conclusions During vibratory densification, the bulk density and the angle of repose of the corundum bodies based on hollow granules and a porous filler depend on the type of the filler used and the size of its grains. The relative settling and the relative density of the bodies obtained after densification are related to their bulk density and the angle of repose.We established the dependence of the shrinkage during firing, the apparent density, and the strength of the fired products on the bulk density, the degree of settling, and the relative density of the specimens after vibratory densification. At a given density, the products based on the corundum granules exhibit higher strength.We developed large-sized corundum products of complex shape for thermal insulation at 1800°C under reducing conditions.Translated from Ogneupory, No. 4, pp. 28–32, April, 1986.     

A novel agglomeration granulating system utilizing a centrifugal-fluidizing drive

Necessary conditions were studied for the optimum operation of agglomeration granulation. The mechanisms that would realize these conditions were investigated by several experiments.On the basis of the results obtained, a novel granulating system involving a surface wetness control mechanism has been developed.The present paper describes the mixing and dispersing characteristics of the coating vessel, the detection method for wetness control, the particular spraying units, and the operating conditions thereof, together with the characteristics of this newly developed powder coating granulation system.This system has been shown to provide an easy and reproducible granulating technique even when products below 1 mm in size are required.     

Composition and formation of fusions of metallurgical magnesite powder

Conclusions In metallurgical magnesite (periclase) powder obtained in rotary kilns of length 50, 75, 90, and 170 m one encounters no less than eight structural genetic types of granules (fusions) in which are selectively concentrated the impurities CaO, SiO₂, etc. The commonest are diabase and dolomite granules.The formation of diabase and clayey (aluminous) fusions is due to the cementation of periclase particles by the melts, formed deposited from the mechanical impurities in the raw material. Morphologically and genetically similar chamotte, and frequently ferruginous, fusions develop as a result of the granulation of aggregate periclase grains of fusible products from the breaking up of the lining in the rotary kilns.The formation of dolomite and diabase-dolomite fusions with an internal core from the products of the decomposition of the broken primary dolomite is connected with the power of the latter to be preserved during firing in the form of lumps, and not subjected (in contrast to magnesite) to self-dispersion.In the formation of granules chemical reactions occur between the periclase, lime, and molten fusible impurities in the magnesite raw materials. The products of the reaction are spinel, magnesioferrite, forsterite, monticellite, merwinite, cordierite, and silicates and ferrites of calcium. In connection with the increase in the concentration of fusible impurities the fusions (granules) are poor quality constitutents of the magnesite powder.Translated from Ogneupory, No. 5, pp.47–54, May, 1971.     

Effect of urea granule size on ammonia volatilization from surface-applied urea

Urea powder and granules of varying size (1 to 8 mm diameter) were surface applied to a ryegrass/white clover pasture. Evolution of NH₃ was measured using a continuous air flow enclosure method. At 30 kg N ha^–1, the percentage of urea-N lost as NH₃ from powder or granules of 1–2, 3–4, 5.6 and 8 mm diameter was 18, 17, 20, 22 and 32 respectively. As the particle size increased, the rate of urea hydrolysis decreased and delayed the time at which the maximum rate of volatilization occurred. Mineral-N and soil surface pH measurements confirmed that during the period of volatilization, urea moved less than 30 mm from the application point.For the powder and 3–4 mm granule treatments, when the application rate was increased from 30 to 300 kg N ha^–1, the percentage of urea-N volatilized increased, but at any particular rate there was no significant difference in percentage loss between the powder and 3–4 mm granules.     

Granulation of finely crystalline ammonium sulphate using calcium oxide and sulphuric acid

Two types of finely crystalline ammonium sulphate (particle size distributions: white type 7% 2–3 mm, 45% 1–2 mm, 48% <1 mm; blue type 1% 2–3 mm, 8% 1–2 mm, 91% <1 mm) were granulated by adding calcium oxide and concentrated sulphuric acid using a rotating drum in the laboratory and pilot plant. The granules had satisfactory physical and chemical properties.The granules made in the pilot plant with 25 kg ammonium sulphate, 0.5 kg CaO, 1.26 litres of water and 0.9 to 1.125 litres of 98.5% H₂SO₄ had 80 to 97% of the granules within the size range of 1–3 mm, abrasion resistance of 0.4 to 0.8% <1 mm, crushing strength of 1.4 to 2.3 kg, critical relative humidity of 65–70%, pH 1.8 to 1.9 and N, S and Ca contents of 19, 24 and 1%. The quality of the granules when stored for 6 months alone or blended together with common fertilizers did not change.A glass house trial using barley demonstrated that the agronomic values of 4 prototype ammonium sulphate granules produced in the laboratory were similar to 3 standard granular ammonium sulphate fertilizers.The process of granulation which could easily be adopted in superphosphate manufacturing plants is recommended for plant scale testing.Provisional New Zealand Patent (No 236,025) applied for.     

Technological parameters of corundum chamotte

Conclusions It has been established that to obtain densely sintered macrocrystalline corundum chamotte it is most expedient to obtain the briquet in the form of granules 20–25 mm in diameter from finely ground GK alumina (or special alumina brands of high purity) followed by annealing at 1900–1950°C.Translated from Ogneupory, No. 3, pp. 31–36, March, 1980.     

Optimizing the properties of corundum-based thermal insulation products using the method of experimental planning

Conclusions In order to optimize the properties of the corundum-based thermal insulation products, a study was conducted on the effect of granulometry and the type of the filler using the method of experimental planning.It was shown that increasing the limiting size of the filler grains decreases the apparent density and the ultimate compressive strength independent of the type of the filler.Using the method of correlation-regression analysis, it was established that the weight content of the grains of the 2–3 mm fraction must not exceed 20% in the charge for obtaining products which can simultaneously satisfy the requirements of (low) apparent density and (high) ultimate compressive strength.Based on the complex studies, we worked out the production technology and obtained a trial batch of corundum-based thermal insulation products withstanding a service temperature up to 1750°C.Translated from Ogneupory, No. 6, pp. 15–17, June, 1987.     

Effect of process parameters on the crush strength of granular fertiliser

The granulation characteristics of nitro-phosphate-based NPK fertiliser have been investigated in a bench scale drum granulation unit. It was found that the granulation of the fertiliser took place in the growth regime. Crush strength analysis of the final granulate was undertaken and was correlated with particle size and fractional saturation. The experimental data and analysis in this study indicate that that the rounded, regular-shaped granules produced by granulating with higher liquid phase ratio and fractional saturation result in the granules having stronger bonds between sub-granules and lower porosity.     

Vibrational molding of ceramic concretes. Molding systems and the regularities of the process

Conclusions We developed a vibrational molding process for obtaining ceramic concretes using rigid mixtures and metallic molds. The as-formed semifinished products are characterized by a fairly high mechanical strength. A siliceous (silica-based) ceramic concrete having a porosity of 12–16% and an ultimate compressive strength of 20–25 N/mm² was obtained. The mechanism of structure evolution of the semifinished products was identified; it is determined by the interaction between the phases and fixing (orientation) of the liquid phase of the highly concentrated binder suspensions due to the molecular forces of the filler grains.The decisive effect of the binder on the mechanical properties of the ceramic concretes was established. On decreasing the binder content of the ceramic concretes from 39 to 12%, their specific strength increases by 4 times.Translated from Ogneupory, No. 6, pp. 8–14, June, 1993.     

Granulation of a hardmetal powder for spark plasma sintering

A fluidized bed granulation method, pressure swing granulation (PSG), was applied to granulation of a hardmetal powder without pressing lubricants for making the upstream process of spark plasma sintering (SPS) more efficient.

The properties of the granules were examined and compared with those of spray dried granules and extruded ones under the present system using a sieve.

Spherical granules between 0.15 and 0.84 mm in diameter difficult to obtain by the spray drying were obtained with high yield. The flowability of the granules was far better than that of spray dried granules and similar to that of extruded ones. Iron contamination and oxidization during pressure swing granulation were tolerable to the real production.     

Preparing limestone for burning

Conclusions Classification of limestone before burning can be done by the screening method on 20 and 8 mm screens. Segregation of material into the fractions 3–8 and 0.5–3mm should be done with plant incorporating a fluidized bed which permits more complete use to be made of the raw materials, increases the specific loading compared with screens, improves the quality of the classification products, and contributes to an increase in the quality of the fired products, and enables us to use the heat of the waste gases from the calcination units.Translated from Ogneupory, No.6, pp. 18–21, June, 1967.     

Influence of the properties of refractory powders on their granulation and the properties of the granules

Conclusions A study was made of the properties of aluminosilicate powders of various compositions and their influence on the densification during granulation.We established relationships between the porosity and density of the granules with various concentrations of Al₂O₃ with bulk densities and angles of natural slope. It is shown that to obtain dense and strong green articles and fired aluminosilicate granules with the minimum shrinkage, it is necessary to use bodies with a high bulk density and low internal friction, which is attained for alumina by using batches with the maximum concentration of -Al₂O₃ and grains with a pore-free structure, and for aluminosilicate refractories — an increased content of Al₂O₃ within the limits of each type of article.Translated from Ogneupory, No. 8, pp. 6–10, August, 1985.     

Heat-resistant composites based on a ternary binder suspension

Conclusions Combining the processes of mechanical wet milling of a ternary mixture (quartz sand, scrap of the MKS-83 refractories, and monoclinic zirconium dioxide) and topochemical interaction between its particles and the ions of dissociated sodium silicate facilitates the formation of a gelatinous coating at the surface of the particles and, thereby, imparts adhesiveness (bonding capacity) to the suspensions and ensures thermal volume constancy of the castings.We established the optimum pH value of the suspension for attaining its minimum viscosity and obtaining the maximum levels of the ultimate bend strength of the castings (4–5 N/mm²) and minimum open porosity (18–19%).Based on the obtained suspensions and a corundum filler (the 2–0.5 mm and the minus 0.5-mm fractions), we developed casting bodies and obtained ceramic concretes (firing temperature 1400°C) having an ultimate bending strength of 28 N/mm² and capable of withstanding 54 thermal cycles (1300°C — water).Translated from Ogneupory, No. 1, pp. 4–7, January, 1992.     

Manufacture of Granulated Chitosan

Conditions for dry-wet spinning of spherical chitosan granules 0.5–2.0 mm in diameter into a two-layer spinning bath consisting of immiscible liquids are proposed, where an organic liquid, decane in particular, is the upper layer of the bath while a solution of ammonium hydroxide is the lower layer. The possibility of obtaining chitosan microgranules from 2 to 30 µm in diameter by emulsification of a solution of chitosan in decane or a solution of an anion-active surfactant — sodium dodecyl sulfate — is demonstrated. The effect of the molecular weight and concentration of the solutions on the granule-forming power of chitosan is established. A 6% solution of chitosan with a molecular weight of 200 kD is recommended for further studies.__________Translated from Khimicheskie Volokna, No. 5, pp. 26–29, January–February, 2005.     

Process for production of calcined phosphate in a grate furnace

Experimental results on bench scale production of calcined phosphate in a grate furnace are presented. Phosphate concentrates were mixed with silica, sodium carbonate and charcoal in varying amounts and granulated (4–6 mm), in some cases with the aid of phosphoric acid. The granules were dried and calcined at 1140–1300°C in a grate furnace. Products with 24.4 to 30.7% total P₂O₅ were obtained with solubility higher than 70% in 2% citric acid.Other experiments were done employing pelletized (4–6 mm) sugar cane bagasse as fuel instead of coal. In these cases, the raw materials silica, sodium carbonate and phosphate concentrates were granulated and then mixed with the pelletized sugar cane bagasse. Two products with 26.1 and 29.4% total P₂O₅ containing respectively 18.8 and 24.0% soluble P₂O₅ (in 2% citric acid solution) were obtained by calcination at temperatures of 930 and 1300°C respectively.The products of both experiments were mainly citric acid-soluble phosphates (rhenanite and andoite) with small amounts of non-reacted apatite.     

Determination of the material composition of the finely milled binder in magnesic-spinellid refractories

Conclusions Our studies concerning the selection of the optimum dispersed component of the magnesic-spinellid refractories established that the system containing 40–50% chromium ore and 50–60% sintered periclase makes it possible to obtain refractory products having high levels of physical and ceramic characteristics and an increased resistance to the action of molten slags.Translated from Ogneupory, No. 5, pp. 5–7, May, 1989.     

橡胶硫化促进剂N-环己基-2-苯并噻唑次磺酰胺的团粒法造粒技术

采用团粒(聚)法制备了橡胶硫化促进剂N-环己基-2-苯并噻唑次磺酰胺(CBS)粒状产品,确定了团粒造粒工艺的最佳条件,并在此条件下进行了稳定运行实验.结果表明,用脱水后含水率为20%的CBS湿粉料为造粒原料,采用团粒法制备CBS粒状成品的最佳工艺条件:黏结剂乙烯-乙酸乙烯酯共聚物质量分数为CBS干基料的8%、湿粒含水率为34.77%,造粒盘倾角为35～45°、造粒盘转速为65 r/min,黏结剂乳液喷加时间约为10 min,造粒周期为50～60 min,烘箱干燥温度为(55±2) ℃,烘干时间为210 min;在最佳工艺条件下制得的粒状CBS性能均达到指标要求:初熔点不小于96.0 ℃,粒径为2.0～4.5 mm,粒子的平均强度在2.0～8.0 N,加热减量不大于1.00%,灰分不大于0.40%,成粒率超过60%.该粒状CBS能完全取代粉状产品,对橡胶的硫化性能无不良影响.     

Hot press compaction of magnesium oxide obtained by decomposing certain compounds

Conclusions A study was made of the densification during hot pressing at 1300–1600°C of magnesium oxide activated by decomposing the hydroxide and the basic magnesium hydrocarbonate. During decomposition of these compounds at 500–700°C with a soak of 15 min, magnesium oxide forms that is actively compacted almost to the theoretical density (98.5–99.5%) at relatively low temperatures (1500–1600°C) and pressures of 150 kg/cm².We investigated the influence of the time and temperature of heat processing of the hydroxide and the basic hydrocarbonate of magnesium on the fineness of the grains and the defects of the crystalline lattices of periclase thus formed, and also on the capacity for subsequent compaction during hot pressing.The reduction in the degree of compaction during hot pressing of the materials, heat processed at temperatures below 500°C, is due to the increase in the content in them of undecomposed residue, which hinders the diffusion sintering in subsequent stages of pressing.A reduction in the degree of compaction with rise in temperature of heat processing above 500°C or with an increase in the heat-processing time with the optimum temperature, is connected not with a reduction in the defects of the crystalline lattice of the periclase formed, but with the sizes and physical state of its particles.We also studied the effect of additions of magnesium oxide obtained by heat processing the hydroxide or the basic hydrocarbonate of magnesium on the compaction during hot pressing of industrial magnesia. The introduction of 10–20% of this additive ensures a reduction in the optimum pressing temperature of 100–300°C and an increase in the density of the specimens almost to theoretical.Translated from Ogneupory, No.2, pp.46–53, February, 1967.