磷矿的湿法分解研究现状

为提高磷矿的利用率,用不同的分解剂对不同区域、不同品位的磷矿进行湿法分解的研究备受关注。作者通过分析磷矿的湿法分解研究现状,从工艺和动力学机理2个方面对磷矿在不同分解剂下的分解过程研究进行归纳综述,并展望了进一步研究的方向。     

胶磷矿生产磷酸的研究

对胺磷矿的组成和性质，胺磷矿的反应活性、发泡及消泡性能，湿法磷酸制备及磷酸的浓缩和澄清进行了试验研究。结果表明：用大峪口胺磷矿作原料，可生产出浓度为50％～51％P2O5的磷酸，符合生产高效磷肥的要求。     

碳酸盐新型捕收剂PA—31选矿试验研究

贵州省瓮福磷矿英坪矿段矿石属碳酸盐型磷块岩。在磨矿细度－２００目６１．２％。Ｐ２Ｏ５品位３０．７１％，ＭｇＯ３．７６％的条件下，采用硫酸为磷矿物的抑制剂，ＰＡ—３１为碳酸盐矿物捕收剂的反浮选工艺，获得精矿Ｐ２Ｏ５品位３５．８６％，ＭｇＯ０．８％，Ｐ２Ｏ５回收率９７．２０％的指标。     

The recovery of the lanthanides from phosphate rock

Phosphate rock contains up to 1% lanthanide (rare earths) oxides present in isomorphous substitution for Ca²⁺. Lanthanum, cerium and neodymium form about 80% of the total. When the rock is leached with H₂SO₄ the lanthanides are mostly (about 70%) lost in the gypsum residue. When the rock is leached with HNO₃ or HC1, more than 80% can be recovered without interference with fertiliser production. At an annual production of 130 million tons, phosphate rock represents an important source of lanthanides. The different methods of recovery are reviewed.     

A review of the studies on phosphate rock for agricultural use in China

Since the early 1940's, systematic studies on phosphate rock (PR) for agricultural use have been made in China. These covered the following aspects: Mineralogical properties of phosphate rock materials, including svanbergite; Ability of different plants to absorb phosphorus from PR; Effect of soil properties on the availability of PR to plants; Technologies for processing powdered PR.Since these studies are mostly published in Chinese [4, 6, 7, 8, 9, 11, 15, 16, 17, 18], they are virtually unknown to agronomists and soil scientists outside China. The present article is a comprehensive review of the studies on PR for agricultural use carried out in China during the last 50 years.It is shown that because of the easily decomposable properties of certain Chinese PR's, the limited industrial potentialities in present day China (particularly the shortage of sulphuric acid), the large areas of strongly acid red soils in Southern China, the introduction of legume crops in the rotation, and the planting of perennial trees, notably rubber in tropical areas, the direct application of powdered PR for agricultural use appears to be very advisable.     

An empirical analysis of the simultaneous effects of nitrogen, phosphorus and potassium in millet production on spatially variable fields in SW Niger

Low soil fertility is a major constraint for increasing millet production on the acid sandy soils of the West African Sahel. On these soils, all three macronutrients: nitrogen (N), phosphate (P) and potassium (K), may be expected to limit crop yields. The important question is therefore: which of them is the most critical and would, if applied in small amounts, increase yields significantly? This paper addresses this question with an empirical approach, thus avoiding the commonly observed difficulty in the interpretation of agronomic research, caused by the extreme local soil variability which characterizes Sahelian coversands. We actually exploit soil variability by using novel non-parametric techniques for data exploration in combination with spatial methods of parametric model estimation. Apart from N, P and K, the effects of surface crusting, local topography, manure levels, farmer behaviour and spatial dependence are taken into account, since these may confound the true effects of N, P and K. A quadratic formulation conforms best to the data and explains 81 percent of the yield variation. The equation highlights the importance of interactions among variables and thus confirms the possible impact of native soil conditions on the outcome of fertilizer treatments in experimental research. The results of much earlier, multi-year, research are confirmed remarkably well by this single year study. In addition, a spatially explicit assessment on the crop response to increasing nutrient levels highlights that blanket fertilizer applications are inefficient, because yield increases in some places will be accompanied by yield decreases at other sites. Cash-constrained farmers therefore have to resort to precision farming techniques to maximize returns from minimal external input packages. However, a large part of the good explanation of millet yield variability over space derives from spatial autocorrelation, and not directly from topsoil N, P and K. This calls for further research on the factors that affect millet yield and on the characterization and classification of sites, followed by experimental work to design site-specific fertilizer technologies.     

Application strategies for Sechura phosphate rock use on permanent pasture

At two phosphate (P) responsive sites in hill country the effectiveness of Sechura phosphate rock (SPR) as a direct application P fertilizer for permanent pasture was evaluated. Sechura was applied at two rates, in three different application strategies. The treatments were 16.7 and 50 kgP ha^–1 annually, 25 and 75 kgP ha^–1 biennially, and 50 and 150 kgP ha^–1 triennially giving a total of 50 and 150 kgP ha^–1, respectively, over three years. Single superphosphate (SSP) served as the standard P fertilizer. A comparison was also made between SPR and Chatham Rise phosphorite (CRP), another reactive PR. Total pasture and legume production and P uptake by pasture was measured with all fertilizer treatments over a three year period.In the year of application, SPR was as effective as SSP in stimulating total pasture and legume production and P uptake by pasture. This reflects the very reactive nature of this PR. In the second and third years of measurement, SPR did not show superior residual efffects to SSP. The ability of CRP to stimulate legume growth more than SPR in the second year following application demonstrates the danger of generalizing about the residual effects of reactive PR materials. Of the application strategies evaluated, a biennial appplication of 25 kgP ha^–1 as SPR maintained legume growth at a higher level than a smaller (16.7 kgP ha^–1) annual dressing. The biennial strategy also increased total pasture yield, in addition to legume production to a greater extent in the second and third years than a single (50 kgP ha^–1) triennial application.     

The effects of nitrogen fertilizer form on the plant availability of phosphate from soil,phosphate rock and mono-calcium phosphate

A glasshouse trial using lettuce as the test crop, and laboratory incubations were used to evaluate the influence of various nitrogen fertilizers on the availability of phosphate from an unfertilized loamy sand soil and from the same soil fertilized with Sechura phosphate rock or monocalcium phosphate. The order in which nitrogen fertilizer form increased plant yield and P uptake from soil alone and from soil fertilized with the rock was ammonium sulphate > sulphurised urea > ammonium nitrate > urea > potassium nitrate. For each rock application (both 30 and 60 mg/pot) and for soil alone, increased P uptake by the plant correlated well with decreased soil pH. In soil fertilized with the soluble P form, monocalcium phosphate, the form of the nitrogen fertilizer had little effect on plant P uptake. Subsequent laboratory incubation studies showed that increased dissolution of soil-P or Sechura phosphate rock did not occur until acidity, generated by nitrification or sulphur oxidation of the fertilizer materials, had lowered soil pH to below 5.5. A sequential phosphate fractionation procedure was used to show that in soils treated with the acidifying nitrogen fertilizers, ammonium sulphate and urea, there was considerable release of Sechura phosphate rock P to the soil, amounting to 42% and 27% of the original rock P added, respectively.     

Dissolution of phosphate rocks in soils. 2. Effect of pH on the dissolution and plant availability of phosphate rock in soil with pH dependent charge

The effect of soil pH on the dissolution of phosphate rocks (PRs) and the subsequent availability of the dissolved inorganic phosphorus (Pi) to plants was examined in a volcanic soil adjusted to different pH values. Potassium dihydrogen orthophosphate (KH₂PO₄) and three PRs, Nauru (NPR), Jordan (JPR) and North Carolina (NCPR) were incubated with the pH-amended soils at a rate of 800µg P g^–1 soil for 84 days. The extent of PR dissolution was determined by measuring the increases in the amount of 0.5 M NaOH extractable Pi (NaOH-P) in the PR treated soil over the control soil. The amount of plant available P was measured either by extracting with 0.5 M NaHCO₃ or by growing ryegrass in soil samples incubated with the phosphate sources.At each pH the order of the extent of PR dissolution followed NCPR > JPR > NPR, which was consistent with the decreasing order of their chemical reactivities. As the pH decreased from 6.5 to 3.9 the dissolution of PRs increased from 29.3% to 83.5%, from 18.2% to 78.9%, and from 12.5% to 60.3% for NCPR, JPR and NPR, respectively. In contrast, as the soil pH decreased from 6.5 to 3.9, the proportion of the dissolved P extracted by 0.5 M NAHCO₃ decreased from 38% to 5% and the proportion taken up by ryegrass plants decreased from 46% to 7%. This decrease in plant available P corresponded to an increase in the adsorption of inorganic P with a decrease in pH. However, the uptake of P from PR relative to that from KH₂PO₄ was higher at low pH than at high pH. Further, the amount of P taken up by plants was more closely related to the amount of NaHCO₃ extractable P than to the amount of dissolved P present in the soil.     

宜昌磷矿采空区处理的实践与思考

介绍并分析了宜昌磷矿开发30多年来采空区处理的典型实例，对今后如何加强该矿区采空区处理工作提出了若干建议。     

Influence of rates of reactive phosphate rock and sulphur on potentially available phosphorous in organically managed soils in the south-eastern near-Mediterranean cropping region of Australia

Reactive phosphate rock (RPR) is the only phosphorous (P) fertiliser allowed for organically managed, broad-acre crop-pasture systems in southern Australia. However, soils are usually deficient in P, and the soils, climate, and plant species grown, do not promote extensive dissolution of RPR so the fertiliser is poorly effective for crop and pasture production. Biological oxidation of elemental sulphur (S) mixed and applied with RPR may sufficiently increase dissolution of P from RPR to improve its effectiveness as a P fertiliser. However, this needs to be confirmed in field studies in the region. Rates of RPR and S required to optimise dissolution of RPR are not known for the soils, environments, and agricultural systems used. Both pot and field studies showed that mixing RPR and S, and incorporating the mix into soil (top 10 cm for field studies), significantly increased Olsen P and soil solution P, even in strongly acidic soils (pH_Ca < 4.6). In general, Olsen P increased linearly with the applied rate of P up to 42–70 kg P ha⁻¹ and the rate of change in Olsen P per unit of applied P increased with the applied rate of S up to 400 kg S ha⁻¹. This interaction suggested that the effectiveness of RPR + S may be compromised by segregation of RPR and S. In addition, there was evidence that S application may not necessarily create a more acidic soil environment necessary for enhanced dissolution of RPR.     

Evaluation of application timing in fertilizer micro-dosing technology on millet production in Niger,West Africa

Micro-dosing technology has been developed by the International Crops Research Institute for the Semi-Arid Tropics (ICRISAT) and its partners to help subsistence farmers in the Sahel improve inorganic fertilizer application. However, the ICRISAT's recommendations regarding fertilizer application through this technology are only applicable at sowing and do not allow any flexibility in terms of labor and/or capital management. In rural areas, fertilizer cannot always be applied at sowing due to financial and labor constraints. The purpose of this study was to evaluate the effect of the timing of fertilizer application on millet production. A 2-year on-station experiment and a 1-year on-farm field experiment were conducted in the western region of Niger, West Africa. Even under the heterogeneous climatic conditions of the region during our experimental period, the results showed that the trend was the same as observed in previous studies: millet production improved through fertilizer application compared to the control (without fertilizer). The harvest index was also higher compared to that of the control. This increased production was consistently the same for all application timings. The marginal value–cost ratio on the investment calculated using a budgeting analysis for the on-farm experiment showed that – regardless of application timing – millet farmers who fertilized their fields with inorganic fertilizer made more profit than those who did not (control). This was also true for farmers who were unable to fertilize at sowing – delayed application was still the more profitable option relative to the no fertilizer control. Our results indicate that small subsistence farmers can be offered more options for inorganic fertilizer application timing using the micro-dosing technology. Delayed inorganic fertilizer application can help small farmers who are often labor constrained at the sowing period improve their yields as well as their economic returns.

Effect of type and level of roughage offered to sheep and urine addition on compost quality and millet growth and production in the Sahel

A greenhouse trial was carried out at the International Crop Research Institute for the Semi-Arid Tropics (ICRISAT), at Sadoré (13°15′ N, 2°18′ E), Niger. Experiments were conducted in conjunction with a feeding trial. The feeding trial yielded eight types of compost made from faeces and leftovers with or without urine addition from sheep fed either bush straw or millet stover offered at 60 or 80 g dry matter (DM) kg⁻¹ live weight (LW). In the second trial the agronomic value of composts to a millet crop was evaluated. The level of roughage on offer did not affect compost quality. Urine addition increased N content in composts (P<0.05), but had no effect on P. Millet stover based composts contained 24% more N and 42.5% more P than composts made with bush straw (P<0.05). Urine addition enhanced millet growth between 15 and 60 days after planting (DAP), increased millet aboveground mass by a factor 2.8, and increased the efficiency of N and P use by 100% and 50%, respectively. Millet response (growth, phytomass, N and P uptake, apparent efficiency of N and P use) to urine addition was higher with millet stover based composts than with bush straw based composts (P<0.05). It was concluded that addition of urine during composting of roughage leftovers and faeces from stall-fed animals could significantly improve nutrient recycling and consequently the productivity of mixed farming systems of semi-arid West Africa. This revised version was published online in November 2006 with corrections to the Cover Date.     

Investigation of the changes of P2O5 content of phosphate rock during simultaneous calcination/sulfation

In this study, the changes of P₂O₅ content of phosphate rock during simultaneous calcination/sulfation in a fluidized-bed were investigated. P₂O₅ determination was carried out on samples with and without quenching of sulfated rock. The effects of the temperature and particle size on P₂O₅ content of either sample were determined. It was found that the decrease in process temperature favorably increased the P₂O₅ content of the sulfated samples. Since the calcination was the dominant reaction during the early stages of the process, there was an initial increase in P₂O₅ content of the sulfated samples. However, at later stages, there was a decrease in P₂O₅ extent of sulfated samples with an increase in the extent of CaSO₄ formed during the reaction. The P₂O₅ extent, on the other hand, increased with decreasing particle size. The results showed that P₂O₅ content of 23.27% in raw ore may be increased up to 36% following the quenching of sulfated samples.     

充填浮选柱正-反浮选胶磷矿工艺研究

通过充填浮选柱浮选胶磷矿的工艺实验,提出了串联操作的正一反浮选流程,得到了较为合适的工艺条件,为生产放大提供了理论依据。     

Influence of pH,time and rate of application on phosphate rock dissolution and availability to pastures

Soil Samples were collected from a field experiment conducted to evaluate the agronomic effectiveness of a reactive phosphate rock (PR), Sechura sand, relative to that of monocalcium phosphate (MCP) at different soil pHs and rates of application. The samples were analysed for P soluble in the soil solution and bicarbonate extractable P. The rate of dissolution of PR was calculated from the data on the fractionation of inorganic P. In MCP plots P in the soil solution decreased sharply with time especially at low pHs and high rates of fertiliser application. In PR plots the concentration remained with time at the same as or a slightly higher level than that was found one month after application. Solution concentration of P was lower at very high rates of PR application than at intermediate rates. In both MCP and PR plots bicarbonate extractable P decreased with increasing pH. Bicarbonate extractable P was linearly related to MCP but not to PR applied. The rate of dissolution and the proportion of PR dissolved decreased with increasing rates of PR application but the amount dissolved increased. Phosphate dissolved at high level of PR application did not seem to enhance proportionately either the concentration of P in soil solution or bicarbonate extractable P.     

利用磷矿石干法制磷(复)肥的研究

本文介绍了磷矿石的资源概况、结构性质,简要慨述了我国磷矿直接开发的工艺,详细地讨论和分析了干法磷复肥的研究工艺,探讨了干法中存在的问题,对今后的研究方向提出了建议.     

药剂不同添加方式对胶磷矿浮选的影响研究

对云南某风化质磷矿进行了在不同加药点添加调整剂YP1和YP11的浮选对比试验,结果表明,YP1和YP11加入到磨机中的试验结果优于加入到浮选槽中的结果.