硅酸盐水泥熟料中A矿包裹物、方镁石、还原矿物及煤灰沉落的岩相观察

本文通过岩相观察水泥熟料中的一些非主要矿物。如A矿包裹物,方镁石,还原矿物,对熟料中煤灰沉落点的B.矿区域也做了观察。通过观察总结了这些次要矿物的存在形态,并对形成原因及关联的工艺含意进行了分析,观察这些非主要矿物对判断规烧工艺状况。了解凝烧进程具有一定的帮助。

农村固体废弃物堆肥胡敏酸还原土壤Fe^(3+)矿物研究

堆肥胡敏酸作为农村固体废弃物资源化处置的重要产物,除具有保水保肥的功能外,还具有氧化还原特性。针对农村固体废弃物堆肥胡敏酸结构特性,进行了堆肥全过程胡敏酸结构演变对土壤Fe^(3+)矿物还原特性研究。结果表明,随堆肥进行,堆肥胡敏酸芳香化、腐殖化加剧,氧化还原功能基团、组分含量增加,可有效促进土壤Fe^(3+)矿物还原。醌基团是堆肥胡敏酸重要的氧化还原功能基团,堆肥中后期木质纤维素降解释放醌基团,经缩合作用与堆肥胡敏酸结合加速堆肥腐殖化进程,增强堆肥胡敏酸氧化还原性能,提升Fe^(3+)矿物还原能力。

微波技术在冶金中的应用

在简要概述微波加热基本原理和用于冶金基础研究现状的基础上,着重评述了微波辐射技术在磨矿、湿法浸取、干燥、废物处理和矿石还原等冶金领域中的最新进展. 大量研究实例表明,用微波强化传统冶金单元操作过程可以显著地减少操作时间并提高效率,具有良好的经济价值和潜在的工业化前景. 最后详细论述了微波冶金亟需解决的问题,展望了今后的研究开发方向.

大洋地幔橄榄岩-铬铁矿中的金刚石和深地幔再循环

全球多地蛇绿岩型地幔橄榄岩和铬铁矿中发现微粒金刚石,并在中国西藏南部和俄罗斯乌拉尔北部的蛇绿岩铬铁矿中发现原位产出的金刚石,认为是地球上金刚石的一种新的产出类型,不同于金伯利岩型金刚石和超高压变质型金刚石。它们与呈斯石英假象的柯石英、高压相的铬铁矿和青松矿等高压矿物以及碳硅石和单质矿物等强还原矿物伴生,指示蛇绿岩中的这些矿物组合形成于深度150~300 km或者更深的地幔。金刚石具有很轻的C同位素组成(δ13C-18‰^-28‰),并出现多种含Mn矿物和壳源成分包裹体。研究认为它们曾是早期深俯冲的地壳物质,达到>300 km深部地幔或地幔过渡带后,经历了熔融并产生新的流体,后者在上升过程中结晶成新的超高压、强还原矿物组合,通过地幔对流或地幔柱作用被带回到浅部地幔,由此建立了一个俯冲物质深地幔再循环的新模式。蛇绿岩型地幔橄榄岩和铬铁矿中发现金刚石等深部矿物,质疑了蛇绿岩铬铁矿形成于浅部地幔的已有认识,引发了一系列新的科学问题,提出了新的研究方向。

氧化性入井液对富有机质页岩渗透率的影响

富有机质页岩沉积于缺氧的还原环境,富含黄铁矿、绿泥石和有机质等还原性组分。油气储层开发过程中有大量氧化性入井液进入储层,与储层岩石流体不配伍,打破页岩储层与油气水等地层流体的物理和化学平衡状态。选取四川盆地川东南彭水地区志留系龙马溪组富有机质页岩开展氧化性流体与富有机质页岩作用实验,分析氧化性入井液对页岩储层渗透率的影响。研究结果表明,富有机质页岩接触氧化性流体后,渗透率会随着流体氧化还原电位(Eh)的变化而改变,即氧敏性;流体氧化还原电位小于450 mV时,产生Fe2O3、Fe(OH)3、菱铁矿(FeCO3)、二水硫酸钙(CaSO4·2H2O)、MgSO4和BaSO4等化学沉淀固相微粒和页岩岩屑固相微粒,导致页岩渗透率降低。调控入井流体Eh来抑制氧敏损害,发挥氧化致裂增渗作用,是处于还原环境下油气藏储层保护完井液的发展方向。

Separation of alumina and silica from metakaolinite by reduction roasting-alkaline leaching process: Effect of CaSO_(4) and CaO

Limestone(CaCO3),which could promote sulfur fixation,was added to coal gangue during roasting in a circulating fluidized bed(CFB)boiler.CaO and CaSO_(4) were the main Ca-bearing minerals while metakaolinite was the major Al-bearing mineral in CFB slag.The effect of CaSO_(4) and CaO on the separation of alumina and silica from metakaolinite by reduction roasting−alkaline leaching process was studied.Results showed that metakaolinite was completely converted into hercynite and silica solid solutions(i.e.,quartz and cristobalite solid solutions)by reduction roasting with hematite.More than 95%of silica in the reduced specimen was removed by alkaline leaching.The addition of CaSO_(4) and CaO remarkably decreased the separation efficiency of alumina and silica in metakaolinite,which could be attributed to the formation of Si-bearing minerals:(1)Fayalite and anorthite were formed during the reduction roasting process;(2)Fayalite was stable while anorthite was converted into sodalite and wollastonite during the alkaline leaching process.This study demonstrates that sulfur in coal gangue should be fixed by treating the exhaust gas instead of controlling the combustion process of CFB to achieve the comprehensive recovery of silica and alumina from the CFB slag.

Preparation of titanium mineral from vanadium titanomagnetite concentrates by hydrogen reduction and acid leaching

Titanium mineral was prepared from vanadium titanomagnetite concentrates by hydrogen reduction and acid leaching.The leaching behaviors of elements like Fe,V,Mn,Al,Mg,Ca,and Si were highly related to the reduction degree.The phase compositions of the reduced materials and the leached residues were analyzed by XRD to identify the effect of reduction degree on the leaching mechanisms.The results showed that the concentrates were reduced to iron metal and titanomagnetite at 800-1000°C for 0.5 h,and the above elements of Fe and impurities were easily leached.Deeper reduction led to the formation of ilmenite and Mg-Al spinel,which hindered leaching.Mg-bearing anosovite appeared in the further reduced materials,and the leaching rates of impurities became much lower.An upgraded titanium mineral with a normalized TiO_(2) grade of 70.3%was achieved by H_(2) reduction at 850°C for 0.5 h and acid leaching,which is a satisfactory Ti resource for the preparation of titanium oxide by sulfate process.

Effect of calcium compounds on direct reduction and phosphorus removal of high-phosphorus iron ore

The increasing demand for iron ore in the world causes the continuous exhaustion of magnetite resources.The utilization of high-phosphorus iron ore becomes the focus.With calcium carbonate(CaCO_(3)),calcium chloride(CaCl_(2)),or calcium sulfate(CaSO_(4))as additive,the process of direct reduction and phosphorus removal of high-phosphorus iron ore(phosphorus mainly occurred in the form of Fe_(3)PO_(7) and apatite)was studied by using the technique of direct reductiongrinding-magnetic separation.The mechanism of calcium compounds to reduce phosphorus was investigated from thermodynamics,iron metallization degree,mineral composition and microstructure.Results showed that Fe_(3)PO_(7) was reduced to elemental phosphorus without calcium compounds.The iron-phosphorus alloy was generated by react of metallic iron and phosphorus,resulting in high phosphorus in reduced iron products.CaCO_(3) promoted the reduction of hematite and magnetite,and improved iron metallization degree,but inhibited the growth of metallic iron particles.CaCl_(2) strengthened the growth of iron particles.However,the recovery of iron was reduced due to the formation of volatile FeCl_(2).CaSO_(4) promoted the growth of iron particles,but the recovery of iron was drastically reduced due to the formation of non-magnetic FeS.CaCO_(3),CaCl_(2) or CaSO_(4) could react with Fe_(3)PO_(7) to form calcium phosphate(Ca_(3)(PO_(4))_(2)).With the addition of CaCO_(3),Ca_(3)(PO_(4))_(2) was closely combined with fine iron particles.It is difficult to separate iron and phosphorus by grinding and magnetic separation,resulting in the reduced iron product phosphorus content of 0.18%.In the presence of CaCl_(2) or CaSO_(4),the boundary between the generated Ca_(3)(PO_(4))_(2) and the metallic iron particles was obvious.Phosphorus was removed by grinding and magnetic separation,and the phosphorus content in the reduced iron product was less than 0.10%.

Effects of basicity and temperature on mineralogy and reduction behaviors of high-chromium vanadium-titanium magnetite sinters

The effects of basicity and temperature on the reduction process of Hongge high-chromium vanadium-titanium magnetite(HCVTM)sinter were investigated in this work.The main characterization methods of X-ray fluorescence(XRF),X-ray diffraction(XRD),scanning electron microscope(SEM),and metallographic microscope were employed in this study.In this work,the reduction of HCVTM sinter with different temperature and basicity were experimented.The Fe,FeO,and TiO in reductive samples increase with increasing basicity and temperatures.The increase of basicity and temperature is favorable to the reduction of HCVTM sinter.The Fe phase has out-migration tendency to the surface of sinter while the perovskite and silicate phases have in-migration tendency to the inside of sinter.The reduction degradation index(RDI)decreases while the reduction index(RI)increases with increasing basicity.The RI increases from 67.14%to 82.09%with increasing temperature from 1073 K to 1373 K.

Effects of minerals in ferric bauxite on sodium carbonate decomposition and volatilization

Direct reduction is an emerging technology for ferric bauxite utilization. However, because of sodium volatilization, its sodium carbonate consumption is considerably higher than that in ordinary bauxite processing technology. TG-DSC and XRD were applied to detecting phase transformation and mass loss in direct reduction to reveal the mechanism on sodium volatilization. The results show that the most significant influence factor of ferric bauxite on sodium volatilization in direct reduction system is its iron content. Sodium volatilization is probably ascribed to the instability of amorphous substances structure. Amorphous substances are the intermediate-products of the reaction, and the volatilization rate of sodium increases with its generating rate. These amorphous substances are volatile, thus, more sodium is volatilized with its generation. A small amount of amorphous substances are generated in the reaction between Na2CO3 and Al2O3; thus, only 3.15% of sodium is volatilized. Similarly, the volatilization rate is 1.87% in the reaction between Na2CO3 and SiO2. However, the volatilization rate reaches 7.64% in the reaction between Na2CO3 and Fe2O3 because of the generation of a large amount of amorphous substances.

TG–FTIR analysis of pyrolusite reduction by major biomass components

Pyrolusite reduction processes by three major biomass components cellulose,hemicelluloses and lignin,represented by CP,HP and LP,respectively,were investigated by thermogravimetric analyzer coupled with Fourier transform infrared spectrometry(TG-FTIR).The Sestak-Berggren(SB) equation was used to evaluate the kinetics of reduction processes.TG analysis reveals that the main reduction processes occur at 250-410 ℃,220-390 ℃,and 190-410 ℃ for CP,HP,and LP,respectively.FT-IR and XRD results indicate that various reducing volatiles(e.g.aldehydes,furans,ketones and alcohols) are produced from the pyrolysis with the three major components,which directly reduce MnO_2 in ore to MnO.The processes are described by the SB equation with three parameters(m,n,p).Their non-zero values suggest that pyrolusite reduction is controlled by the diffusion of reducing gaseous products through an ash/inert layer associated with minerals.The apparent activation energies for pyrolusite reduction by CP,HP and LP are 40.48,25.70 and 40.10 kJ·mol^(-1),respectively.

Effects of Cd on reductive transformation of lepidocrocite by Shewanella oneidensis MR-1

We investigated the reduction of lepidocrocite(γ-FeOOH) by Shewanella oneidensis MR-1 in the presence and absence of Cd. The results showed that Cd^(2+) retarded microbial reduction of γ-Fe OOH and avoided formation of magnetite. The inhibitory effect on γ-Fe OOH transformation may not result from Cd^(2+) toxicity to the bacterium; it rather was probably due to competitive adsorption between Cd^(2+) and Fe^(2+) on γ-Fe OOH as its surface reduction catalyzed by adsorbed Fe^(2+) was eliminated by adsorption of Cd^(2+).

Laboratory Obtaining of Ferroalloy after Reduction of Oxides from Waste Product and Natural Resource

The Obrochishte deposit located in the Republic of Bulgaria has considerable reserves of relatively poor carbonate manganese ore. At the same time, in the country there are operative outputs for the production of sulphuric acid where vanadium catalyst is deactivated and discharged, polluting the environment. The utilization of these materials requires their consolidation to proper sizes with regard to the next processing, as the most suitable method for joint consolidation is agglomeration. The present work explores the preliminary calculations for obtaining agglomerate and obtaining an alloy with high and low carbon content, through carbothermic and aluminothermic agglomerate reduction.

Characterization of semi-coke generated by coal-based direct reduction process of siderite

Solid wastes derived from metallurgical industries pose a significant threat to environment. The utilization and disposal of these solid wastes are the major concern in the world. Semi-coke generated in coal-based direct reduction process of iron ore is a by-product and its suitable utilization is not available so far. In order to handle it properly, the characteristics of this by-product were comprehensively investigated. A series of analysis methods were used to demonstrate its mineral compositions, petrography and physico-chemical properties. The results reveal that the semi-coke has poor washability. The fixed carbon content of semi-coke reaches 76.11% and the gross calorific value is 28.10 MJ/kg, both of which are similar to those of traditional sinter coke breeze. Also, semi-coke ash possesses lower content of SiO2, Al2O3, S and higher content of CaO and MgO, which could improve the strength of sinter ore when partially substituting for coke breeze in sintering. Semi-coke features well-development porous structure and higher reaction activity, which predicts that the sintering speed could be elevated to some extent when employing it as a partial replacement of coke breeze, so the studies further suggest that the potential adverse effect of the high reactivity on sintering process could be weakened by adequately coarsening the semi-coke's particle size.

红土镍矿选择性还原焙烧过程中的相变转化

针对传统选矿方法难以回收低品位红七镍矿中有价金属镍的问题,采用选择性还原焙烧法研究了不同焙烧温度以及不同焙烧时间条件下红土镍矿(Ni品化为1.49%)中发生的微观结构变化以及相变转化.通过X射线衍射、扫描电镜及X射线能谱分析等测试手段分析表明,在不同焙烧温度及不同时间条件下经选择性还原后的红土镍矿中,镍氧化物逐渐被还原成镍铁合金相,铁氧化物主要转变成浮氏体相,硅酸盐主要以橄榄石形式存在.最后通过还原焙烧磁选试验证实,还原剂为烟煤,添加剂为NCS,两者用量分别为原矿质量的2%和7%,在1200℃条件下焙烧50min,磁选分离得到镍铁产品中镍品位为9.78%,镍的回收率为92.06%,镍铁回收率差为62.51%,实现了红土镍矿中镍铁的选择性还原.

红土镍矿富集镍和铁的焙烧、氢气还原和磁选分离

对印尼红土镍矿的基础特性进行了系统的研究，发现矿石主要由蛇纹石和辉石组成，其中Ni元素主要以类质同象的形式取代Mg元素存在于蛇纹石中．在此基础上分别进行了红土镍矿焙烧、氢气还原、磁选分离镍和铁的一系列实验研究．红土镍矿与碳酸盐添加剂进行混合焙烧实现了Ni和Fe氧化物的释放；对焙烧产物进行氢气还原，还原产物中Ni和Fe元素以金属形态存在，Fe金属化率最高超过80％，远大于原矿还原产物中Fe的金属化率（4％-8％），且随着温度升高，Ni元素易与Fe结合生成Fe—Ni；磁选所得产物中Ni和TFe品位分别达到3％和20％，Fe和Ni的回收率分别达到80％和90％，初步实现Ni和Fe的富集．

印度尼西亚海砂氧化性球团氢气还原机理

对印度尼西亚海砂矿氧化性球团氢气还原的规律做了较详细的研究.实验采用失重的方法,通过对反应过程的物相变化、热力学以及动力学方面的分析,探究了海砂球团矿氢气还原的机理.结果表明:温度在800℃和850℃,还原反应的最终产物主要是Fe Ti O3,整个反应限制环节是由两个不同阶段的过程组成,反应开始阶段由界面化学反应控制,之后由界面化学反应与内扩散共同控制;在900、950和1000℃三个温度下,反应产物中有钛氧化物出现,整个还原反应由三个不同的限制性环节组成,开始由界面化学反应控制,反应中间阶段是由界面化学反应和内扩散共同控制,反应后期则是由内扩散控制为主.

煤基处理硫酸渣制备含硫钢原料的实验研究

以含有低熔点FeS2的硫酸渣和烟煤为原料,对硫酸渣含碳球团进行还原熔分,考察了碱度、焙烧温度、焙烧时间和C/O摩尔比对铁回收率的影响,确定了最佳工艺参数.在碱度R=1.0、焙烧温度1450℃、焙烧时间20 min以及配煤量C/O=1.2的条件下还原熔分硫酸渣,可以获得93.1%铁回收率的珠铁.对尾渣的X射线衍射分析可知,硫酸渣中铁氧化物及含铁硫化物被还原,铁回收率较高,且熔分时间短造成大量铁以金属态滞留于渣中;还原熔分硫酸渣所得珠铁因其较高硫含量,可用于冶炼硫系易切削钢.

Stabilization of S_(3)O_(4) at high pressure:implications for the sulfur-excess paradox

The amount of sulfur in SO2 discharged in volcanic eruptions exceeds that available for degassing from the erupted magma.This geological conun drum,known as the"sulfur excess",has been the subject of considerable interests but remains an open question.Here,in a systematic computational investigation of sulfur-oxygen compounds under pressure,a hitherto unknown S_(3)O_(4) compound containing a mixture of sulfur oxidation states+11 and+IV is predicted to be stable at pressures above 79 GPa.We speculate that S_(3)O_(4) may be produced via redox reactions involving subducted S-bearing minerals(e.g.,sulfates and sulfides)with iron and goethite under high-pressure conditions of the deep lower mantle,decomposing to SO2 and S at shallow depths.S_(3)O_(4) may thus be a key intermediate in promoting decomposition of sulfates to release SO2,offering an alter native source of excess sulfur released during explosive eruptions.These findings provide a possible resolution of the"excess sulfur degassing"paradox and a viable mechanism for the exchange of S between Earth's surface and the lower mantle in the deep sulfur cycle.