石煤钒矿提钒工艺技术的研究进展

介绍了国内外石煤钒矿的资源概况,阐述了石煤钒矿的钠化焙烧、无盐焙烧、钙化焙烧和酸(碱)浸出提取五氧化二钒的工艺,并讨论了各工艺的优点及存在的问题。     

DY-P磷捕收剂在北方某磷矿选矿试验研究中的应用

为了提高北方某磷矿的磷资源利用率,利用DY-P磷捕收剂对该磷矿进行了选矿试验研究。结果表明:DY-P磷捕收剂对该磷矿具有广泛的适应性,受温度影响较小。闭路试验可获得磷精矿品位P2O5达38.12%,回收率达89.45%,杂质铁含量为1.07%,不但降低了铁的含量,而且使选矿药剂成本也大大降低。     

含钒粘土矿两段浸出提钒工艺

采用碱浸预处理-酸浸提钒的两段浸出工艺从含钒粘土矿中浸出钒, 考察了碱浸预处理工序中NaOH用量和浸出时间、预处理后酸浸工序中H₂SO₄用量、浸出温度、浸出时间、液固比等因素对钒浸出率的影响。碱浸预处理能部分溶解Si、Al矿物, 从而破坏含钒矿物晶体结构, 为酸浸提钒时提高钒浸出率并降低酸耗创造条件。实验结果表明, 在95 ℃温度下用20%NaOH对矿样浸出24 h后, 酸浸工序中H₂SO₄用量30%, 温度95 ℃, 液固比1.5∶1, 浸出时间12 h, 钒浸取率达到了80%以上。     

凝胶法制备氮化钒的研究

考察凝胶法制备氮化钒时的氮化温度、氨气流量和氮化时间等因素对产品氮化率的影响。结果表明,氮化温度为750℃,氨气流量为80 m L/min,氮化时间为14 h时,产品氮化率达到95%,其晶粒大小平均在100 nm左右。     

Enhanced lithium-ion intercalation properties of coherent hydrous vanadium pentoxide-carbon cryogel nanocomposites

Coherent hydrous vanadium pentoxide (V₂O₅·nH₂O)-carbon cryogel (CC) nanocomposites were synthesized by electrodeposition of vanadium pentoxide onto the porous carbon scaffold which was derived from resorcinol (R) and formaldehyde (F) organic hydrogels. As-fabricated nanocomposites were characterized by scanning electron microscopy (SEM), along with EDAX and nitrogen sorption isotherms which suggested vanadium pentoxide incorporated in the pores of carbon cryogels. The nanocomposites showed much improved discharge capacity and better cyclic stability as compared to hydrous vanadium pentoxide films deposited on platinum foil. The discharge capacity of the nanocomposites reached 280 mAh g⁻¹ based on the mass of the vandium pentoxide at a current density of 100 mA g⁻¹ and it possessed good cycle stability at different discharge rates. The results demonstrated that electrochemical performances, such as specific discharge capacitance and reversibility of the composite electrode, could be greatly enhanced by the introduction of carbon cryogels (CCs) scaffold with three-dimensionally interconnected porous structure in which V₂O₅·nH₂O homogeneously dispersed.     

The combined effect of fertiliser nitrogen and phosphorus on herbage yield and changes in soil nutrients of a grass/clover and grass-only sward

The combined effect of reduced nitrogen (N) and phosphorus (P) application on the production of grass-only and grass/clover swards was studied in a five-year cutting experiment on a marine clay soil, established on newly sown swards. Furthermore, changes in soil N, P and carbon (C) were measured. Treatments included four P (0, 35, 70 and 105 kg P ha^–1 year^–1) and three N levels (0, 190 and 380 N kg ha^–1 year^–1) and two sward types (grass-only and grass/clover). Nitrogen was the main factor determining the yield and quality of the harvested herbage. On the grass-only swards, N application increased the DM yield with 28 or 22 kg DM kg N^–1, at 190 or 380 kg N ha^–1 year^–1, respectively. The average apparent N recovery was 0.78 kg kg^–1. On the grass/clover swards, N application of 190 ha^–1 year^–1 increased grass production at the cost of white clover, which decreased from 41 to 16%. Phosphorus application increased grass yields, but did not increase clover yields. A positive interaction between N and P applications was observed. However, the consequences of this interaction for the optimal N application were only minor, and of little practical relevance. Both the P-AL-value and total soil P showed a positive response to P application and a negative response to N application. Furthermore, the positive effect of P application decreased with increasing N application. The annual changes in P-AL-value and total soil P were closely related to the soil surface surplus, which in turn was determined by the level of N and P application and their interaction. The accumulation of soil N was similar on both sward types, but within the grass-only swards soil N was positively affected by N application. The accumulation of organic C was unaffected by N or P application, but was lower under grass/clover than under grass-only.     

Crop yield, nitrogen uptake and nitrate-nitrogen accumulation in soil as affected by 23 annual applications of fertilizer and manure in the rainfed region of Northwestern China

Application of chemical fertilizers and farmyard manure affects crop productivity and improves nutrient cycling within soil–plant systems, but the magnitude varies with soil-climatic conditions. A long-term (1982–2004) field experiment was conducted to investigate the effects of nitrogen (N), phosphorus (P), and potassium (K) fertilizers and farmyard swine manure (M) on seed and straw yield, protein concentration, and N uptake in the seed and straw of 19-year winter wheat (Triticum aestivum L.) and four-year oilseed (three-year canola, Brassica napus L. in 1987, 2000 and 2003; one-year flax, Linum usitatisimum L. in 1991), accumulation of nitrate-N (NO₃-N) in the soil profile (0–210 cm), and N balance sheet on a Huangmian soil (calcaric cambisols, FAO) near Tianshui, Gansu, China. The two main plot treatments were without and with farmyard swine manure (M); sub-plot treatments were control (Ck), N, NP, and NPK.␣The average seed yield decreased in the order MNPK ≥ MNP > MN ≥ NPK ≥ NP > M > N > Ck. The average effect of manure and fertilizers on seed yield was in the order M > N > P > K. The seed yield increase was 20.5% for M, 17.8% for N, 14.2% for P, and 2.9 % for K treatment. Seed yield response to fertilizers was much greater for N and P than for K, and it was much greater for no manure than for manure treatment. The response of straw yield to fertilization treatments was usually similar to that of seed yield. The N fertilizer and manure significantly increased protein concentration and N uptake plant. From the standpoint of increasing crop yield and seed quality, MNPK was the best fertilization strategy. Annual applications of N fertilizer and manure for 23 successive years had a marked effect on NO₃-N accumulation in the 0–210 cm soil profile. Accumulation of NO₃-N in the deeper soil layers with application of N fertilizer and manure is regarded as a potential danger, because of pollution of the soil environment and of groundwater. Application of N fertilizer in combination with P and/or K fertilizers reduced residual soil NO₃-N significantly compared with N fertilizer alone in both no manure and manure plots. The findings suggest that integrated and balanced application of N, P, and K fertilizers and␣manure at proper rates is important for protecting soil and groundwater from potential NO₃-N pollution and for maintaining high crop productivity in the rainfed region of Northwestern China.     

一种4-甲基邻苯二甲腈的合成方法

介绍了一种采用酰胺脱水法合成4-甲基邻苯二甲腈的方法,同时考察了反应温度、时间和脱水试剂等因素对收率的影响。以4-甲基苯酐为原料,通过氨解反应得到4-甲基邻苯二甲酰胺,再经过脱水反应得到扣甲基邻苯二甲腈。同时确定了脱水反应的最佳条件：选择三氯氧磷为脱水试剂,65-70℃反应5h。产物经红外结构鉴定,总收率为74。7％。...     

Anthropogenic nutrient sources and loads from a Mediterranean catchment into a coastal lagoon: Mar Menor, Spain

The Mar Menor is a coastal lagoon increasingly threatened by urban and agricultural pressures. The main watercourse draining into the lagoon is the Rambla del Albujón. A fortnightly campaign carried out over one annual cycle enabled us to characterize the treated urban sewage effluents and agricultural sources which contribute to the nutrient fluxes in the watercourse. Multivariate analysis provided information for establishing chemical signatures and for assessing the relative influence of the various sources on the water quality at the outlet. Mass balances were used to examine net gains and losses, and cross-correlations with rainfall to analyze climatic influence and control factors in the trends of the nutrient flux. The rainfall pattern was significantly cross-correlated with nitrate and phosphorus fluxes from agricultural sources, while fluctuations in the resident population explained the phosphorus flux trend in urban sources. 50% of dissolved inorganic nitrogen was from agricultural sources, while 70% of total phosphate and 91% of total organic carbon were from urban point sources. The net amounts of all the nutrients fell as a result of plant uptake and/or denitrification in the channel. The control of urban point sources (phosphorus-enriched) is suggested as a promptly action for improving the health of the coastal lagoon.     

On the issue of limiting nutrient and predictions of cyanobacteria in aquatic systems

This study aims at bridging the gap between freshwater and marine eutrophication studies by presenting (1) a cross-system analysis of the relationship between chlorophyll and the total nitrogen (TN) to total phosphorus (TP) ratio (2) a general model to predict concentrations of cyanobacteria from data on TP, the TN/TP ratio, salinity and temperature, and (3) a general trophic level classification for aquatic systems based on chlorophyll classes (for oligo-, meso-, eu- and hypertrophic systems). The data compiled in this study concerns more than 500 lakes and coastal areas covering a very wide domain in terms of nutrient concentrations and salinity. There was no simple relationship between the TN/TP ratio and empirical chlorophyll concentrations or concentrations of cyanobacteria. Variations in TP rather than TN generally seem to be more important to predict variations among systems in chlorophyll-a and cyanobacteria. Different "bioavailable" forms of the nutrients (DIN, DIP, phosphate, nitrate, etc.) have been shown to have very high coefficients of variation (CV), which means that many samples are needed to obtain reliable empirical data which are necessary in models aiming for high predictive power and practical usefulness.