32P isotopic techniques for evaluating the agronomic effectiveness of rock phosphate materials

Tropical soils are often low in available P and therefore require inputs of P fertilizer for optimum plant growth and production of food and fiber. The cost of applying imported or locally produced, water-soluble, P fertilizers is often greater than utilizing indigenous phosphate rock. Therefore quantifying the P availability of soils amended with phosphate rock-based products in a variety of crop management and environmental conditions in developing countries is desirable for making recommendations on best type and rate of fertilizers to use to obtain maximum agronomic and economic benefits. One adequate approach for evaluating the agronomic effectiveness of rock phosphate materials is through the use of³²P/³³P isotopic tracers. The present paper describes the principles and assumptions of the³²P isotopic techniques commonly used in the field and greenhouse for the agronomic evaluation of rock phosphate materials. An overview of the applications of these techniques is also given.     

Agronomic evaluation of fertilizer products derived from Sukulu Hills phosphate rock

Partial acidulation of phosphate rock (PR) or compaction of PR with soluble P fertilizers can improve the usefulness of unreactive PR for use as P fertilizer. A greenhouse study was conducted to evaluate nonconventional phosphate fertilizers derived from a low reactive Sukulu Hills PR from Uganda. Raw PR (which contained 341.0 g kg^–1 Fe₂O₃), beneficiated or concentrate PR, partially acidulated PR (PAPR) and PR compacted with triple superphosphate (TSP) were evaluated. Compacted materials had a P ratio of PR:TSP = 50:50. PAPR materials were made by 50% acidulation with H₂SO₄. TSP was used as a reference fertilizer. Fertilizers were applied to an acidic (pH = 5.4) Hiwassee loam (clayey, kaolinitic, thermic Rhodic Kanhapludults) at rates of 0, 50, 100, 200, 300 and 400 mg P kg^–1 soil. Two successive corn (Zea mays L.) crops were grown for 6 weeks. Compacted concentrate PR + TSP and raw PR + TSP were 94.4 and 89.7% as effective as TSP, respectively, in increasing dry-matter yields for the first corn crop. PAPR from the concentrate was 54.8% as effective as TSP. Raw PR, concentrate PR and the PAPR from the raw PR were ineffective in increasing dry-matter yields. The same trends were obtained when P uptake was used to compare effectiveness. Ineffectiveness of the raw PR and its corresponding PAPR was attributed to a high Fe₂O₃ content in the raw PR. Bray I and Pi paper were found to be nearly equally suitable at estimating available P in the soils treated with responsive fertilizer materials. Mehlich 1 overestimated available P in soil treated with raw PR, concentrate PR or the PAPR from the raw PR.     

Long-term residual value of North Carolina and Queensland rock phosphates compared with triple superphosphate

The effectiveness of large single applications of North Carolina reactive rock phosphate, Queensland non-reactive rock phosphate, and Calciphos, were compared to the effectiveness of superphosphate in field experiments in south-western Australia for up to 11 years after application. As measured using plant yield, superphosphate was the most effective fertilizer in the year of application, and relative to freshly-applied superphosphate, the effectiveness of the superphosphate residues declined to be about 15 to 65% as effective in the year after application, and 5 to 20% as effective 9 to 10 years after application. Relative to freshly-applied superphosphate, all the rock phosphates were 10 to 30% as effective in the year of application, and the residues remained 2 to 20% as effective in the 10 years after application. The bicarbonate soil test reagent predicted a more gradual decrease in effectiveness of superphosphate of up to 70% 10 years after application. For rock phosphate, the reagent predicted effectiveness to be always lower than for superphosphate, being initially 2 to 11% as effective in the year after application, and from 10% to equally as effective 10 years later. Therefore rock phosphates are unlikely to be economic alternatives to superphosphate in the short or long term on most lateritic soils in south-western Australia.     

Mussoorrie rock phosphate-pyrite mixture as phosphate fertilizer

Mussoorrie rock phosphate (MRP), MRP + pyrite (25% by weight), diammonium phosphate (DAP), ammonium polyphosphate (APP) and nitrophosphate (NP) were compared in a field experiment as fertilizers for wheat. At 20 kg P ha^–1, MRP was only 6 per cent as effective as DAP. However, when it was mixed with pyrite, the efficiency of MRP increased to 64 per cent at 20 kg P ha^–1 compared with 97 per cent at 40 kg P ha^–1. The P requirement for a targeted yield for 4.5 t ha^–1 decreased from 39.4 kg P ha^–1 as MRP to 23.7 kg P ha^–1 as MRP + pyrite. Of the other P fertilizers studied, NP was as effective as DAP, whereas APP was 9 to 37 per cent more effective than DAP. However, the P requirement as DAP, NP and APP for a targeted yield of 4.5 t ha^–1 was similar (11 ± 0.5 kg P ha^–1).     

普通过磷酸钙工艺技术之我见

普通过磷酸钙的生产工艺技术，因矿的品质不同而各异。磷矿粉是生产的物质基础，应抓好这一环节。这里着重介绍云南的磷矿干法生产工艺技术。     

Removal of the tetravalent actinide thorium from solution by a biocatalytic system

The aim of this work was to study the effects of pH, a metal complexing reagent (citrate) and the concentration of substrate on the bioaccumulation of tetravalent actinides, using Th⁴⁺ as a model, by a phosphates-catalysed reaction. This yields HPO which precipitates with heavy metals as cell-bound metal phosphate. Poor removal of The from solution was observed, which is in accordance with the solution chemistry of the metal. A considerable improvement in the efficiency of thorium removal was obtained by incorporating ammonium acetate (NH₄Ac) into the solution. Although extensive deposition of polycrustaling NH₄UO₂PO₄ was observed previously by cells that had accumulated UO, no evidence for deposition of cstalline thorium phosphate was obtained by X-ray diffraction analysis. Examination by proton induced X-ray emission (PIXE) analysis. Examination by proton induced X-ray emission (PIXE) analysis showed a non-homogenous thorium deposit of variable phosphorous content.     

EXTRACTION OF Zn AND Cd FROM CHLORIDE LIQUORS BY TRI-n-BUTYL PHOSPHATE

Studies have been made on the extraction of Zn and Cd by TBP(tri-n-butyl phosphate)from diluent hydrochloric acid solutions of soldium chloride.The experiments show that thespecies extracted from diluent HCI solutions of NaCl appear to be predominantly ZnCl_2·2TBP and CdCl_2·2TBP.For Cd,at lower acidities,anionic complexes of the typeH_2CdCl_3 are also extracted.As the acidity is increased,H_2CdCl_4 appear to be predominantcomplexes in organic phase.For Zn,the acidocomplexes of the type HZnCl_3 appear in organ-ic phase after the acidity of solutions reaching a certain value([HCl]>0.1 mol/L).Furthermore,the ultraviolet absorption spectra of both aqueous and organic phases have beenstudied,and the infrared spectra of the organic phases have been exomined.The extractionmechanism and temperature effect are also discussed.     

2—乙基己基膦酸单（2—乙基己基）酯—Mn萃合物的研究

通过固态萃合物2-乙基己基膦酸单(2-乙基己基)酯(HEH(EH)P,HA)-Mn的制备,对单烷基膦酸酯萃取二价Mn离子的萃合物组成及萃取机理进行了研究。结果表明:萃合物为不含水分子,组成为MnA_2,属高旋弱场配合物;认为萃合物为四面体结构。     

透波材料的透波原理及现状分析

在初步了解透波材料的基础上,阐述了透波材料的应用需求,分析了磷酸盐体系透波材料透过电磁波的原理,论述了磷酸盐体系透波材料的研究现状,并指出了发展方向。     

Use of nanoparticles to make mineral oil lubricants feasible for use in a residential air conditioner employing hydro-fluorocarbons refrigerants

The application of nano-fluids in refrigerating systems is considered to be a potential way to improve the energy efficiency and reliability of HVAC&R facilities and to make economic the use of environment-friendly refrigerants. In this paper, we report a method that uses nanoparticles to enhance the energy efficiency of retrofitted residential air conditioners (RAC) employing HFCs as alternative refrigerants. The reliability and performance of RAC with nanoparticles in the working fluid have been investigated experimentally. A new mineral-based nano-refrigeration oil (MNRO), formed by blending some nanoparticles (NiFe₂O₄) into naphthene based oil B32, was employed in the RAC using R410a as refrigerant. A method showing how to disperse the NiFe₂O₄ nanoparticles in the mineral oil refrigeration lubricants is presented together with an investigation of their stability. The solubilities of the new MNRO in R134a, R407C, R410a and R425a were measured. The performances of the RAC, such as the cooling/heating capacity, the power input and the energy efficiency ratio, were determined. The results indicate that the mixture of R410a/MNRO works normally in the RAC. The cooling/heating EER of the RAC increased about 6% by replacing the Polyol-Easter oil VG 32 lubricant with MNRO.