Effect of magnesium sulphate addition to urea on nitrogen loss due to ammonia volatilization

Fertilizer was applied as urea alone or as a mixture of urea and magnesium sulphate (MgSO₄·1H₂O) to study the effect on ammonia volatilization under laboratory conditions in relation to soil texture, N:Mg ratio, air flow rate, fertilizer form (solid or liquid) and organic material. When the mixture of urea and magnesium sulphate (UMM) was applied at a ratio of 1:0.21, significantly lower NH₃-N losses than from urea were found in 2 of 6 soils, and 4 soils showed a similar tendency. Increasing the N:Mg ratio to 1:0.5 resulted in significantly lower NH₃-N loss. Lower air flow rates reduced ammonia loss from UMM more than from urea alone. The effectiveness of UMM over urea was not improved in the liquid form. Increase of organic material had no influence on NH₃-N loss from urea alone or UMM.     

锌渣浸出渣高温挥发富集铟锗试验研究

为了有效富集生产硫酸锌后酸浸渣中的稀散金属锗和铟,进行了锌渣浸出渣高温挥发富集铟锗试验.试验结果表明,高温挥发富集稀散金属铟、锗工艺可行.当原料配比为锌渣浸出渣:石灰:煤粉:碳粉:硫化物=100:20:8:8:2时,在1 100℃温度下硫化挥发2 h,铟、锗和砷的挥发率均达到90%以上.     

Dynamics of ammonia volatilization from simulated urine patches and aqueous urea applied to pasture I. Field experiments

Ammonia (NH₃) volatilization losses from simulated sheep urine patches in a perennial ryegrass (Lolium perenne L.)/white clover (Trifolium repens L.) pasture in New Zealand were measured in the field during the summer, autumn and winter periods. An enclosure technique was used with microplots (23 cm diameter) receiving either sheep urine or aqueous urea at rates equivalent to 500 kg N ha^–1 and monitored continuously until measured losses decreased to 0.5% per day. Mean volatilization losses for urine treated plots were 22.2% of the applied N in summer, 24.6% in autumn and 12.2% in winter. Corresponding losses for the urea treated plots were 17.9%, 28.9% and 8.5%. Differences between these two N sources were not significant although the seasonal differences were significant (P 0.05). Changes in NH₃ gas fluxes were found to be related to measured changes in soil pH and air temperature. Two repeated applications of urine or aqueous urea to the same microplot resulted in significantly greater subsequent volatilization losses averaging 29.6% from the second and 37.5% from the third application.Most of the applied N was accounted for as either soil mineral N (NH ₄ ⁺ + NO ₃ ^- + NO ₂ ^- ) or NH_3(g) . Urea hydrolysis was rapid and obeyed the first order kinetics during the 24 hours following application. Calculated half-lives of urea in urine and aqueous urea were significantly different and were 3.0 and 4.7 h respectively during the summer and 4.7 and 12.0 h during the autumn.Implications of the results obtained to practical field situation together with the efficacy of the enclosure technique for measuring volatilization losses are discussed.     

浅谈煤岩分析与应用

介绍了以煤岩分析为核心的煤质综合评价方法,以此来分析判定煤的变质程度,准确定性,区分不同变质程度的混洗煤,有效地控制了进厂煤质量。提出了煤岩配煤理念,对混洗煤的利用更加科学合理,优化了配煤结构,稳定了焦炭质量。     

Insights into internal oxidation of SiC/BN/SiC composites

The article presents new observations of the physical manifestations of internal oxidation and volatilization in SiC/BN/SiC composites. The observations are made on both unbroken and broken minicomposite specimens before and after 12 h exposures at 1000°C in dry air with 10 ppm water vapor. The observations are enabled by a sample preparation method involving ion-mill sectioning and polishing. Complementary analyses of volatilization and closure of resulting gaps are also presented. The observations show that BN is generally consumed in two stages: (i) through reaction with oxygen along the interfaces with both the fiber and the matrix, producing two concentric annular pockets of borosilicate glass and an intervening annulus of progressively thinning BN; and (ii) subsequent volatilization, through the reaction of boria with trace amounts of water vapor in the environment to form borohydroxide gases. The spatial extent to which these processes proceed is governed by a competition between the outward diffusion of reaction gases through both matrix cracks and interface gaps produced by boria volatilization, and the formation of oxides on the newly exposed surfaces of fibers, matrix, and coating.     

难处理金矿焙砂氯化挥发提金试验研究

采用高温氯化挥发法对难处理金矿的焙砂进行提金试验研究,试验考察了氯化温度、氯化时间、氯化剂添加量和干球强度的影响因素。研究结果表明,在氯化温度1150℃、氯化时间1 h、Ca Cl2添加量5%的条件下,金、银的挥发率分别达到98%、60%,而且Si O2、Al2O3、Ca O、Mg O和铁等几乎不挥发,实现金、银等有价元素与脉石分离。根据试验结果,提出一种难处理金矿的焙砂氯化挥发提金新工艺。     

Release of volatiles from large coal particles in a hot fluidized bed

Coal particles with diameters of 3–11 mm were injected into a small, hot bed of sand fluidized by nitrogen. Volatiles evolution was followed by sampling the exit gas stream and subsequent analysis by gas chromatography. Three Australian coals covering a range of volatile matter were studied and the effects of coal particle size and bed temperature were determined. The yields of gaseous components, char and tar are explained by consideration of the competitive reactions for coal hydrogen and oxygen and secondary reactions of the volatile species within the coal particle. The pore structure developed during devolatilization has a significant effect on the extent of these secondary reactions. It is concluded that heat transfer is the main process controlling the volatilization time in fluidized bed combustors. The time required for heat transfer into the coal particle, determined by calculation and experiment, agrees with the measured volatilization time. Significant factors are external heat transfer to the surface of the particle, internal conduction through the coal substance and radiation through the pores, and the counterflow of volatiles out of the coal particle. For different coals, variations in the volatilization time appear to be caused by the development of different pore structures, which affect radiant heat transfer through the pores.     

Thin layer concentrated emulsion copolymerization of PUASi/Styrene/Methyl methacrylate

Stable concentrated emulsions of polymerizable polysiloxane‐containing polyurethane (PUASi)/Styrene (St)/Methyl methacrylate (MMA) were prepared using sodium dodecyl sulphate (SDS)/nonyl polyoxyethylene ether (OS15)/polyvinyl alcohol (PVA) as composite surfactant and azobisisobutyronitrile (AIBN) as initiator. A novel polymerization method, thin layer polymerization was used to carry out the concentrated emulsion copolymerization at 55°C. The effects of TDI/PPG molar ratio, surfactant concentration, different kinds of surfactants, and temperature on polymerization stability were studied. The effects of the thickness of the thin layer, the outside temperature of the reactor, as well as polymerization environment on the volatilization rate of water, and monomer in the system were investigated. The conversion‐time relationships of the thin layer polymerization and the tube polymerization, as well as the effect of polymerization environment on the polymerization rate were also investigated. The morphology of latex particles was determined with transmission electron microscope (TEM). © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Selective removal of arsenic from arsenic-containing copper dust by low-temperature carbothermal reduction

ABSTRACT

To selectively separate arsenic from arsenic-containing copper dust, this paper reports a new method of treating the dust by carbothermal reduction and roasting it with coke powder at low temperatures. The effects of different roasting temperatures, coke powder additions and roasting times are discussed. Optimum conditions were obtained to selectively separate arsenic from other valuable metals. The volatilization rate of arsenic was 97.02% and the content of arsenic in the slag was 0.31%. Other valuable metals were not volatile under the conditions of a 350°C roasting temperature, coke powder addition of 30%wt, coke powder particle size of 0.15–1 mm, and a roasting time of 150 min.     

高锑低银锡阳极泥焙烧脱锑工艺研究

采用旋转管式炉对锡阳极泥进行焙烧,考察氧化气氛、还原气氛和硫化还原气氛三种焙烧方式对锡阳极泥中锑挥发率的影响。结果表明,在硫化还原气氛中,配入30%黄铁矿和10%焦粉量,1 000℃焙烧2h时,锡阳极泥中锑的挥发率达到74.56%。硫化挥发的锡锑分离效果优于氧化挥发和还原挥发,与理论分析一致。