Sulfur phase and sulfur removal in high sulfur-containing bauxite

The sulfur phase in high sulfur-containing bauxite was studied by an X-ray diffraction analysis and a chemistry quantitative analysis.The methods for the removal of different shaped sulfur were also discussed.The results show that sulfur phases in high sulfur-containing bauxites exist in the main form of sulfide sulfur （pyrite） or sulfate sulfur,and the main sulfur forms of bauxites from different regions are not the same.Through a combination of an X-ray diffraction analysis and a chemistry quantitative analysis,the sulfur phases of high sulfur-containing bauxite could be accurately investigated.Deciding the main sulfur form of high sulfur-containing bauxite could provide theoretical instruction for choosing methods for the removal of sulfur from bauxite,and an oxidizing-roasting process is an effective way to remove sulfide sulfur from high sulfur-containing bauxite,the content of S^2-in crude ore in the digestion liquor is above 1.7 g/L,but in the roasted ore digestion liquor,it is below 0.18 g/L.Using the sodium carbonate solution washing technology to wash bauxite can effectively remove sulfate sulfur,the content of the total sulfur in ore is lowered to below 0.2% and can meet the production requirements for the sulfur content.

Sulfuric acid leaching of high iron-bearing zinc calcine

Sulfuric acid leaching of high iron-bearing zinc calcine was investigated to assess the effects of sulfuric acid concentration, liquid-to-solid ratio, leaching time, leaching temperature, and the stirring speed on the leaching rates of zinc and iron. The results showed that the sulfuric acid concentration, liquid-to-solid ratio, leaching time, and leaching temperature strongly influenced the leaching of zinc and iron, whereas stirring speed had little influence. Zinc was mainly leached and the leaching rate of iron was low when the sulfuric acid concentration was less than 100 g/L. At sulfuric acid concentrations higher than 100 g/L, the leaching rate of iron increased quickly with increasing sulfuric acid concentration. This behavior is attributed to iron-bearing minerals such as zinc ferrite in zinc calcine dissolving at high temperatures and high sulfuric acid concentrations but not at low temperatures and low sulfuric acid concentrations.

pH variation mechanism of high sulfur-containing bauxite

In order to fundamentally solve the acidification problem of high sulfur-containing bauxite during storage, by simulating the environment of minerals storage in laboratory, the acidification mechanism and influencing factors of high sulfur-containing bauxite were studied and confirmed using the single variable method to control the atmosphere, water and other variables. The results show that the acidification is mostly caused by the oxidation of sulfur-containing bauxite, which is mainly the natural oxidation of Pyrite(Fe S2), then the alkaline minerals dissolute in the presence of water, leading to the acidification phenomenon, which is influenced by moisture and air flow. Finally, more acid-producing substances are formed, resulting in the acidification of high sulfur-containing bauxite. The acidification of high sulfur-containing bauxite results from the combined effect of the oxygen in the air and water, which can be significantly alleviated by controlling the diffusion of the oxygen in air.

Comprehensive recovery of Fe,Zn,Ag and In from high iron-bearing zinc calcine

A beneficiation-metallurgy combination process is developed to recover Zn, Fe and to enrich In, Ag from high iron-bearing zinc calcine based on our former researches. In gaseous reductive roasting process, the roasting conditions were tested by magnetic separation of roasted product. It is found that the V_(CO)(P_(CO)/(P_(CO+CO_2)) in roasting atmosphere should be maintained below 30% to avoid the generation of zinc iron solid solution(Fe_(0.85-x)Zn_xO), which can bring a decrease of iron recovery in magnetic separation. After roasting, acid leaching and multistage magnetic separation are carried out for the recovery of Zn, Fe and enrichment of Ag and In. About 90% of zinc is extracted and 83% of iron is recovered in the whole process. The Ag mainly enters the tailings with a recovery of 76%, the Ag grade increases from 0.12 g/t in raw materials to 1.18 g/t in the tailings. However, the In mainly enters the iron concentrations and the recovery reaches 86%. This process was proved to be technically feasible and may be a favorable option in the treatment of high iron-bearing zinc material with high Ag or In content.

Effect of High Temperature Calcination on Structure and Properties of Bauxite-based Homogeneous Clinkers

In this paper,the effect of high temperature calcination on the structure and properties of bauxite-based homogeneous clinkers calcined at different temperatures for different durations was studied.The results show that with the rising of calcination temperature and the prolonging of holding time,the volume density of bauxite-based homogeneous clinkers increases and the apparent porosity decreases.After high temperature calcination,the linear expansion of bauxitebased homogeneous clinker is smaller than that of the non-calcined ones.Whether calcined at high temperatures or not,the thermal shock resistance of bauxite-based homogeneous clinkers is good.The crystalline phases of bauxite-based homogeneous clinkers are mainly mullite and corundum.There is more glass phase in the bauxite-based homogeneous clinkers without calcination.After calcination at high temperatures the glass phase content decreases significantly,and the mullite crystals develop better forming the cross-network structure.

Performing High Resolution Seismic Reflection for Mapping Bauxite Layers

The seismic method is able to produce highly accurate images of the Earth's subsurface. Having such detail is not only an important factor in mining, but also in civil engineering. Bauxite exploration attracts both government and industrialists to invest in it because of the high percentage of aluminum present. The economic importance of extracting aluminum from bauxite encouraged us to take this challenge;to image bauxite layers by using a high-resolution seismic reflection method at Al Qassim, Saudi Arabia. Since the subsurface structure of the area is complex, this high-resolution reflection method was carried out along a 2D line with geophone and source interval, with settings at 5 m. The result for the seismic section shows that the depth and thickness of the bauxite layer varied from 20 to 34 m, and 3 to 7 m respectively. In addition, the bauxite layer was sandwiched between clay layers. In order to achieve an even more precise depth than presented by seismic section alone, we tied the drilled wells to the seismic data and we accomplished a well match with an approximation error of 1 - 2 m, which may have been caused by the upper clay layer or by very shallow loose subsurface material. The seismic method thus applied shows the ability to detect significant details within the near surface of the earth, and considers more cost-effective than only drilled wells.

Effects of electrolyte recycling on desulfurization from bauxite water slurry electrolysis

To lower the cost of bauxite electrolysis desulfurization using NaOH solution as the supporting electrolyte, effects of electrolyte recycling on bauxite electrolysis desulfurization were investigated. The results indicate that electrode corrosion, cell voltage, the desulfurization rate and the pH value of the electrolyte have no obvious changes with the increase of cycle times. Additionally, there were some transitive valence S-containing ions in electrolyte after the electrolysis, such as SO3^2-,S2O3^2- . However, most of the sulfur in bauxite was eventually oxidized into SO4^2- into the electrolyte, and these S-containing ions did not affect the recycling utilization for electrolyte.

Effect of Bauxite Aggregate on Properties of Al_2O_3-SiC-C Iron Trough Castables

A1203-SiC-C iron trough castables were prepared using high alumina bauxite clinker GL-90 （ 〉 1 mm ） or homogenized bauxite GL-88 to replace the traditional brown corundum aggregates （ 〉 1 mm ） to reduce the cost of iron trough castables. Effects of the two bauxite aggregates on properties of iron trough eastables were investigated. The results show that the two kinds of bauxite affect flowability, bulk density, strength and slag corrosion resistance of trough castables differently. Compared with homogenized bauxite, high alumina bauxite clinker is more suitable to substitute brown corundum. The castables prepared from the bauxite clinker have similar performances with those prepared from brown corundum, especially used in medium or small blast furnaces with weak thermal impact and lower temperature hot metal. However, in large blast furnaces with severe thermal impact and high temperature hot metal, the performances of the two castables are significantly different. So it is suggested to use the brown corundum based castables in the front gyral zone of the slag skimmer.

Electrochemical behaviors of anode materials and their performance for bauxite desulfurization

Pyrite inside bauxite could be oxidized into soluble S-containing ions by electrolysis, and thus achieving bauxite desulfurization by using filtration. However, S-containing ions in electrolyte had some corrosion effects on electrode, especially for anode. In this work, six kinds of traditional materials were selected as anode, and their corrosion behaviors were examined by using electrochemistry characterization. Tafel and CV curves from simulating electrolyte suggested that their corrosion potentials were in the following order: Ni﹥C﹥SS﹥Fe﹥Cu﹥Pb–Ag. As expected, the desulfurization ratio and cell voltage from bauxite electrolysis were in the following order respectively: Cu﹥Ni﹥Fe﹥SS﹥C﹥Pb–Ag and Ni﹥Fe﹥SS﹥Cu﹥C﹥Pb–Ag. Finally, Ni was proposed a kind of excellent electrode material for bauxite desulfurization from electrolysis.

Preparation and Properties of a New Mediumdensity and High-strength Ceramic Proppant

Based on the needs of the market,a new 52 MPa medium-density and high-strength ceramic proppant was prepared by adopting third grade bauxite and clay as raw materials and using the solid phase sintering method,and the effect of the firing temperature on the microstructure,phase composition and mechanical properties of the ceramic proppant was studied. The broken resistance mechanism of this ceramic proppant was also discussed. The results show that the main phases of the prepared ceramic proppant are mullite and corundum; the broken rates are 3. 92% and 7. 21% under 52 MPa and69 MPa,respectively.

国内高铝粉煤灰提取氧化铝主要技术进展及发展建议

粉煤灰已成为我国排放量最大的工业固废,目前堆存量估计在 30 亿吨以上,如果不及时处理或处理不当,将会对环境造成严重危害。由于其具有高含量的氧化铝,特别是高铝粉煤灰,含量超过38%,被认为是取代铝土矿,生产氧化铝的理想原料之一。近几十年来,高铝粉煤生产氧化铝是一项热门的研究课题,各企业及科研院校均投入了大量的人力和物力,并且取得了一定的成就,提出了不同的工艺路线,部分工艺已经进行了中试试验或者工业化生产。目前,初步形成了三种主要的工艺路线:预脱硅-碱石灰石烧结法、石灰石烧结法、一步酸溶法。文章主要综述了以上三种技术的原理、工艺流程及技术进展,分析其发展难点,同时提出评价和建议。

高硫高铁铝土矿悬浮焙烧同步脱硫除铁试验研究

中国铝土矿资源质量每况愈下,高品位铝土矿资源日渐枯竭,资源问题已成为中国铝工业发展的重要难题,而尚未得到工业规模开发利用的高硫高铁铝土矿属于难利用资源,具有巨大的潜在工业价值,对高硫高铁铝土矿开展脱硫除铁基础研究具有重要的理论与实际意义。针对广西高硫高铁铝土矿综合开发利用难题,采用“悬浮氧化焙烧—还原焙烧—磁选”工艺进行了系统的铝土矿脱硫除铁试验,并利用X射线衍射分析(XRD)、化学物相分析和X射线光电子能谱分析(XPS)等方法,研究了焙烧过程中矿物物相的转化。结果表明,矿物中主要含硫和含铁矿物为黄铁矿,采用“悬浮氧化焙烧—还原焙烧—磁选”工艺可同步实现硫元素的高效脱除和铁元素的富集分离。当悬浮氧化焙烧条件为焙烧温度700℃、焙烧时间40min、O2浓度40%、总气量600mL/min,可获得St为0.396%、脱硫率为98.10%的氧化焙烧产品;然后进行悬浮还原焙烧条件为焙烧温度550℃、焙烧时间20min、CO浓度20%、总气量600mL/min、磁场强度150kA/m时,可获得TFe为54.79%的铁精矿和St为0.248%、TFe为4.37和Al2O3含量为75.27%的富铝矿。此技术大幅度提高了高硫高铁铝土矿的Al2O3含量,有利于后续铝土矿溶出,达到了脱硫除铁提铝的技术目标。该工艺为该类难选高硫高铁铝土矿资源的高效利用提供了一种新的技术途径。

高铁赤泥中铝的赋存状态及铝铁分离技术研究

针对拜耳法高铁赤泥无害化处置与资源化利用难题,研究了高铁赤泥中铝的赋存状态及其对铝铁分离的影响。借助XRD、铁化学物相分析、SEM-EDS等检测手段,研究了高铁赤泥的化学组成、矿物组成以及铝的赋存状态等工艺矿物学特征。查明赤泥的主要组成矿物为褐铁矿、赤铁矿、铝针铁矿和钛铁矿,其中铁主要以针铁矿、赤铁矿的形式存在;铝主要以类质同象存在于针铁矿中,形成铝针铁矿,部分以三水铝石的形式存在,铁铝共生关系密切。赋存于针铁矿中的铝采用常规物理分选方法无法实现铝铁分离,利用磁化焙烧和悬浮焙烧预还原—电炉熔炼工艺分别尝试对高铁赤泥进行铝铁分离,磁化焙烧能够实现赤铁矿、针铁矿向磁铁矿的定向转化,但不能有效破坏铁矿物中铝的类质同象结构,无法实现铝和铁的分离,导致磁选铁精矿中TFe品位低、Al2O3含量高;悬浮焙烧预还原—电炉熔炼工艺能有效实现高铁赤泥的铁铝分离与综合利用,当原料TFe品位为46.85%、Al2O3含量为13.31%时,可获得TFe 92.86%的炼钢用生铁,同时所得到的矿渣产品可以作为生产铝酸盐水泥熟料的原料。可见,悬浮焙烧预还原—电炉熔炼工艺可以有效破坏矿石内部铝和铁类质同象的晶格结构,实现了铝铁的高效分离,为高铁赤泥的无害化处置与资源化利用提供了新途径。

高硫高铁铝土矿脱硫除铁研究进展

铝是人们现代生活中重要的金属材料,铝土矿是生产铝的主要原料,随着国内铝工业的持续发展,铝土矿资源的需求量在逐年增加。但国内铝土矿资源品质较低,供给不足,铝土矿对外依存度较高,严重制约了我国铝资源的供应安全,对我国铝工业的可持续性发展产生较大威胁。为了应对我国高品质铝土矿资源的匮乏问题,开发高硫高铁等复杂难选铝土矿资源,对确保我国铝土矿资源的战略安全至关重要。我国高硫高铁等复杂铝土矿资源量大,约15亿t以上,并伴生其他战略金属资源,目前亟待高效开发,利用先进工艺可实现此类典型贫杂铝土矿的工业化应用。铝土矿中过多的硫杂质和铁杂质会对拜耳法提铝工艺产生不可忽视的影响,如腐蚀设备和管道、增加碱耗和赤泥量、影响氧化铝的质量等。因此,从我国高硫高铁铝土矿的资源现状及特点入手,综述了高硫高铁铝土矿脱硫除铁工艺现阶段的研究进展,总结了浮选脱硫、预焙烧脱硫、生物法脱硫、湿法脱硫等主要脱硫技术及物理法除铁、化学法除铁、生物法除铁等主要除铁技术,探讨了各种工艺的工业化应用水平并列举了几个典型高硫高铁铝土矿的工业化应用实例,将为我国开发利用复杂铝土矿资源提供理论支撑,使难利用铝资源得到有效利用,降低我国对国外铝资源的依赖水平,提高铝土矿资源的保障力。

我国高硫铝土矿脱硫及伴生钴资源综合利用研究进展

铝土矿是战略性紧缺矿产资源,我国高硫铝土矿占比高,其高效开发利用有利于减轻我国铝工业原料的供应压力。针对高硫铝土矿的资源特点,对高硫铝土矿脱硫研究现状进行了总结,综述了预先脱硫和氧化铝生产过程中脱硫的优缺点;并基于浮选脱硫方式,探究了铝土矿中伴生钴资源的综合利用思路。高硫铝土矿脱硫的目标是将硫含量降低到符合氧化铝生产或其他工业应用的要求。焙烧脱硫、浮选脱硫、沉淀法脱硫等是高硫铝土矿脱硫的主要方式。其中,浮选脱硫是脱硫方式中较为成熟的工艺,具有效率高、成本低的优点;浮选脱硫也是伴生钴资源综合利用的关键一步,工业推广前景可观。对高硫铝土矿伴生钴资源进行综合回收,能够提高资源综合利用率,提高国内钴资源的自给率,降低对国外资源的依赖程度。对于高硫铝土矿伴生硫钴资源的回收利用,选冶联合是综合回收硫钴重点攻关方向。

高硫铝土矿脱硫方法研究进展

高品质铝土矿在我国属于紧缺性矿产资源,我国有大量高硫铝土矿资源,但高硫铝土矿冶炼会降低Al_(2)O_(3)溶出率、降低赤泥沉降性能、污染氢氧化铝产品、腐蚀生产设备等,因此高硫铝土矿脱硫技术成为实现其高效综合利用、缓解铝土矿资源短缺的关键。目前高硫铝土矿脱硫技术主要分为预处理脱硫和溶出过程脱硫。预处理脱硫包括浮选法、焙烧法、电化学脱硫、微生物脱硫等。浮选法适合于含硫较低的铝矿石资源,对于低品位、高硫含量的铝矿石则存在浮选药剂用量大、废水排放量大等问题;焙烧法脱硫效率高,但传统堆积焙烧存在焙烧时间长、能耗高等问题;电化学脱硫具有低温、常压、高脱硫率、无二次污染等优点,但存在能耗高、生产规模受限制等问题;微生物脱硫生产成本和能耗较低、环保性较高,但特定菌种对生长环境要求苛刻,培育菌种周期长。溶出过程脱硫包括氧化蒸发法脱硫、沉淀法脱硫和石灰法脱硫等。氧化蒸发法能够清除铝酸钠溶液中大部分S^(2-),但对其他形态硫氧化效果不明显;沉淀法脱硫操作较为简单,但存在脱硫剂成本高,难以应用于实际生产的问题;石灰法只能脱除溶液中SO_(4)^(2-),对其他类型硫离子并未产生显著去除作用。未来,建议从以下几个方向着手解决高硫铝土矿脱硫问题:开发低温高效、低能耗焙烧工艺;改善或者研发新型脱硫捕收剂;筛选高效、易培育菌种,研究混合菌脱硫效果。

低温拜耳法赤泥高温溶出行为

赤泥是氧化铝生产过程中排放的强碱性固体废物,尤其对于三水铝石矿低温拜耳法产生的赤泥,其中含有大量的Al_(2)O_(3)未被溶出,造成资源的极大浪费。以低温拜耳法赤泥为原料,通过高温溶出回收其中的Al_(2)O_(3),系统研究了石灰添加量、循环母液苛碱浓度、溶出温度、固含、溶出时间对Al_(2)O_(3)溶出性能的影响规律,获得了溶出过程中物相转变机理和溶出动力学。结果表明:低温拜耳法赤泥高温溶出过程中,Al_(2)O_(3)溶出率随苛碱浓度、溶出温度、时间的增加而增加,随着石灰添加量和固含的增加而降低。推荐Al_(2)O_(3)的溶出条件为:固含500 g/L、苛碱浓度210 g/L、溶出温度270℃、溶出时间60 min、溶出过程不添加石灰,在此条件下Al_(2)O_(3)溶出率为50.36%,溶出液硅量指数为260。Al_(2)O_(3)溶出过程受内扩散控制,表观活化能为33.46 kJ mol,动力学方程为1-2α3-(1-α)^(2/3)=0.00101×^(e-3346 RT)×t;在高温溶出过程中,一水软铝石发生溶解,同时铝针铁矿转化为赤铁矿,导致氧化铝溶出率提高。

高硫高碳铝土矿拜耳法生产中石灰对碳硫平衡的影响

高硫高碳铝土矿在高温拜耳法溶出生产中碳、硫的进出平衡控制至关重要,关系到溶液体系中碳碱和硫含量对生产的影响是否可控。在配料中石灰是最重要及使用量最大的添加剂,在常规配灰范围内,石灰中含碳量占进入流程总无机碳的30%~40%,经研究石灰配入量和自身含碳量对系统碳、硫进出平衡有明显的影响。生产中,在赤泥C/S比为0.45~1.0时,总体上碳、硫进入赤泥的排出量随配灰的降低而增加,其中C/S容易实现进出平衡,有机碳又比无机碳容易实现进出平衡。在使用高硫高碳铝土矿拜耳法生产中要加大碳的排除,建议根据溶出指标情况尽量降低配灰,通过提高石灰质量或分解母液化灰提前排除石灰中的碳,同时控制矿石硫的含量。

贵州某高硫铝土矿矿物特性研究

以贵州某高硫铝土矿作为研究对象,采用X射线荧光光谱(XRF)、X射线衍射(XRD)、矿物参数自动定量分析系统(MLA)等测试手段结合密度泛函理论(DFT)计算,对该矿石的矿物特性进行研究,研究结果表明,该矿石氧化铝品位为60.97%,硫主要以硫化物的形态存在,含量为3.35%,为典型高硫铝土矿;主要有用矿物为一水硬铝石,主要脉石矿物为伊利石、绢云母、黄铁矿等,一水硬铝石与硅酸盐矿物共伴生关系复杂,常包含微细粒黄铁矿;基于密度泛函理论计算了主要矿物一水硬铝石、黄铁矿、伊利石的弹性性质,三种矿物均呈脆性且非中心受力,受到外力容易破碎,黏土矿物伊利石的弹性模量远小于黄铁矿和一水硬铝石,硬度及耐磨性差,且伊利石各向异性程度更深,更易形成裂缝。说明磨矿过程中,伊利石相对易磨从而优先解离,一水硬铝石和黄铁矿硬度接近,需要细磨才能充分解离。上述结论有助于深入了解铝土矿的矿物特性,并为该类型高硫铝土矿的开发利用提供参考。

高铁高硫铝土矿氧压提质脱硫降铁研究

高铁高硫铝土矿的提质利用对于保障我国铝工业战略矿产资源安全具有重要意义。针对含铁13.66%、硫16.24%的一水硬铝石型高铁高硫铝土矿,主要铁、硫物相为黄铁矿,绘制了Fe-S-H2O系电位-pH图。结果表明,当体系pH小于Fe3+水解临界pH时,能够实现铁、硫的同步浸出。采用加压浸出法处理,在液固比4 mL/g、浸出温度170℃、氧气分压0.20 MPa、保温时间2 h条件下,铁、硫浸出率分别为94.08%和98.34%,浸出渣铁、硫含量分别为1.23%和0.41%,XRD结果表明,浸出渣物相主要为一水硬铝石,实现了高铁高硫铝土矿的提质。浸出液主要溶质为硫酸铁,具有铁、硫进一步资源化利用的潜力。