Preparation,characterization and photocatalytic activity of sulfuric acid-modified titanium-bearing blast furnace slag

The feasibility of reducing Cr(VI)from the aqueous solution by sulfuric acid-modified titanium-bearing blast furnace slag(SATBBFS)as a photocatalyst was investigated.The photocatalysts were examined by X-ray diffraction(XRD),UV-vis diffuse reflectance spectra,thermogravimetric analysis(TG)and Fourier transform infrared spectroscopy(FTIR).The photocatalytic activities of the different catalysts were evaluated by the photocatalytic reduction of Cr(VI)under UV-vis light irradiation.The results show that the photocatalytic activities of SATBBFS catalysts are strongly dependent on CaTiO3-to-TiO2 mass ratio,adsorption capacity and surface acidity,and SATBBFS calcined at 400°C shows a higher photocatalytic activity compared with other catalysts.

Simultaneous preparation of TiO2 and ammonium alum,and microporous SiO2 during the mineral carbonation of titanium-bearing blast furnace slag

In this study,a route for simultaneous mineralization of CO2 and production of titanium dioxide and ammonium alum,and microporous silicon dioxide from titanium-bearing blast furnace slag(TBBF slag)was proposed,which is comprised of(NH4)2 S04 roasting,acid leaching,ammonium alum crystallization,silicic acid flocculation and Ti hydrolysis.The effects of relevant process parameters were systematically investigated.The re sults showed that under the optimal roasting and leaching conditions about 85%of titanium and 84.6%of aluminum could be extracted while only 30%of silicon entered the leachate.84%of Al^3+was crystallized from the leachate in the form of ammonium aluminum sulfate dodecahydrate with a purity up to 99.5 wt%.About 85%of the soluble silicic acid was flocculated with the aid of secondary alcohol polyoxyethylene ether 9(AEO-9)to yield a microporous SiO2 material(97.4 wt%)from the crystallized mother liquor.The Al-and Si-depleted solution was then hydrolyzed to generate a titanium dioxide(99.1 wt%)with uniform particle size distribution.It was figured out that approximately 146 kg TiO2 could be produced from 1000 kg of TBBF slag.Therefore,the improved process is a promising method for industrial application.

Recent progress of efficient utilization of titanium-bearing blast furnace slag

Titanium-bearing blast furnace slag(BFS)has valuable compositions and potential environmental hazardousness.Thus,developing efficient and green approaches to utilize BFS is highly desired for resource economization and environmental protection.In the past decades,many attempts have been adopted to reuse BFS efficiently,and significant advances in understanding the fundamental features and the development of efficient approaches have been achieved.This review provides a comprehensive overview of the latest progress on the efficient utilization of BFS and discusses the mechanism and characteristics of various approaches,along with their application prospects.In particular,the extraction and enrichment of titanium-bearing phases from BFS are highlighted because of the high availability of titanium resources.This systemic and comprehensive review may benefit the design of new and green utilization routes with high efficiency and low cost.

Recovery of titanium,aluminum,magnesium and separating silicon from titanium-bearing blast furnace slag by sulfuric acid curing-leaching

An energy-efficient route was adopted to treat titanium-bearing blast furnace slag(TBBFS)in this study.Titanium,aluminum,and magnesium were simultaneously extracted and silicon was separated by low temperature sulfuric acid curing and low concentration sulfuric acid leaching.The process parameters of sulfuric acid curing TBBFS were systematically studied.Under the optimal conditions,the recovery of titanium,aluminum,and magnesium reached 85.96%,81.17%,and 93.82%,respectively.The rapid leaching model was used to limit the dissolution and polymerization of silicon,and the dissolution of silicon was only 3.18%.The mechanism of sulfuric acid curing-leaching was investigated.During the curing process,the reaction occurred rapidly and released heat massively.Under the attack of hydrogen ions,the structure of TBBFS was destroyed,silicate was depolymerized to form filterable silica,and titanium,magnesium,aluminum,and calcium ions were replaced to form sulfates and enriched on the surface of silica particles.Titanium,aluminum,and magnesium were recovered in the leaching solution,and calcium sulfate and silica were enriched in the residue after leaching.This method could effectively avoid the formation of silica sol during the leaching process and accelerate the solid-liquid separation.

Antibacterial Properties of V-doped Titanium-bearing Blast Furnace Slag Prepared at Different Calcination Temperatures

Perovskite-type V-doped titanium-bearing blast furnace slag (VTBBFS) photocatalyst was prepared by high-temperature solid phase method.The influence of calcination temperature on the photocatalytic and antibacterial properties of VTBBFS was studied in details.Its composition and microstructure were evaluated by X-ray diffractometer,ultraviolet-visible absorption spectrometer,Fourier transform infrared spectrometer and scanning electron microscope.The antibacterial properties of VTBBFS to Candida albicans were investigated by flask oscillation method.The results showed that the optical absorption and antibacterial properties of VTBBFS were the best with 10%(ω) doping of vanadium,prepared at 800℃ for 2 h,and its sterilization rate was close to 100% to Candida albicans (ATCC10231).The minimum inhibitory and minimum bactericidal concentrations were 25 and 50 mg/mL.When the concentration was 0.2 μg/mL,the catalyst had the least toxic toxicity.

Synthesis of Foliar Fertilizer and Ca-S-Si Compound Fertilizer from Titanium-bearing Blast Furnace Slag

With titanium-bearing blast furnace slag, ammonium sulfate, citric acid and potassium carbonate as raw materials to produce foliar fertilizer and Ca-S-Si compound fertilizer by means of heating process for the first time, which improved the solubility of the slag and converted the nutritional elements into such ones which are prone to be absorbed by plants. The effects of process conditions on dissolution rate of titanium were mainly analyzed through the orthogonal experiment. The results showed that the optimum synthesis process conditions of foliar fertilizer from the slag were 360 ℃ for 35 min, the mass ratio of ammonium sulfate and titanium-bearing blast furnace slag was 8：1. Under these conditions more than 80% of iron, titanium, magnesium and part of silicon in titanium-bearing blast furnace slag converted into water-soluble substances and existing in foliar fertilizer. Foliar fertilizer contained nitrogen, sulfur, potassium, iron, titanium, magnesium and silicon, and pH value of foliar fertilizer was 6. Ca-S-Si compound fertilizer mainly contained calcium silicate and calcium sulfate, which existed in the form of citric acid-soluble substance and slightly soluble substance, respectively.

Dry Mix Slag—High-Calcium Fly Ash Binder. Part Two: Durability

This work investigates durability of cement-free mortars with a binder comprised of ground granulated blast furnace slag (GGBFS) activated by high-calcium fly ash (HCFA) and sodium carbonate (Na2CO3): the soundness, sulfate resistance, alkali-silica reactivity and efflorescence factors are considered. Results of tests show that such mortars are resistant to alkali-silica expansion. Mortars are also sulfate-resistant when the amount of HCFA in the complex binder is within a limit of 10 wt%. The fineness of fly ash determines its’ ability to activate GGBFS hydration, and influence soundness of the binder, early strength development, sulfate resistance and efflorescence behavior. The present article is a continuation of authors’ work, previously published in MSA, Vol. 14, 240-254.

Determination of dielectric properties of titanium carbide fabricated by microwave synthesis with Ti-bearing blast furnace slag

The preparation of functional material titanium carbide by the carbothermal reduction of Ti-bearing blast furnace slag with microwave heating is an effective method for valuable metals recovery;it can alleviate the environmental pressure caused by slag stocking.The dynamic dielectric parameters of Ti-bearing blast furnace slag/pulverized coal mixture under high-temperature heating are measured by the cylindrical resonant cavity perturbation method.Combining the transient dipole and large π bond delocalization polarization phenomena, the interaction mechanism of the microwave macroscopic non-thermal effect on the titanium carbide synthesis reaction was revealed.The material thickness range during microwave heating was optimized by the joint analysis of penetration depth and reflection loss, which is of great significance to the design of the microwave reactor for the carbothermal reduction of Ti-bearing blast furnace slag.

Extraction of valuable metals from Ti-bearing blast furnace slag using ammonium sulfate pressurized pyrolysis−acid leaching processes

A novel method of extracting valuable metals from Ti-bearing blast furnace slag(TBBF slag)via pressure pyrolysis of recyclable ammonium sulfate(AS)−acid leaching process was proposed.The results show that when pressurized roasting at an AS-to-slag mass ratio 3:1 and 370℃for 90 min,the extraction rates of titanium,aluminum and magnesium reached 94.5%,91.9%and 97.4%,respectively.The acid leaching solution was subjected to re-crystallization in a boiling state to obtain a titanium product having a TiO2 content of 94.1%.The above crystallization mother liquor was adjusted to pH=6 and pH≥12.2,respectively,and then qualified Al2O3 and MgO products were obtained.The analysis through XRD and SEM−EDS proves that the main phases in roasted samples were NH4AlSO4,CaSO4 and TiOSO4.The thermodynamic analysis presents that the main minerals of perovskite,spinel and diopside in raw ore could spontaneously react with the intermediate produced by AS under optimal conditions.

Dry Mix Slag—High-Calcium Fly Ash Binder. Part One: Hydration and Mechanical Properties

High-calcium fly ash (HCFA)—a residue of high-temperature coal combustion at thermal power plants, in combination with sodium carbonate presents an effective hardening activator of ground granulated blast-furnace slag (GGBFS). Substitution of 10% - 30% of GGBFS by HCFA and premixing of 1% - 3% Na2CO3 to this dry binary binder was discovered to give mortar compression strength of 10 - 30 to 30 - 45 MPa at 7 and 28 days when moist cured at ambient temperature. High-calcium fly ash produced from low-temperature combustion of fuel, like in circulating fluidized bed technology, reacts with water readily and is itself a good hardening activator for GGBFS, so introduction of Na2CO3 into such mix has no noticeable effect on the mortar strength. However, low-temperature HCFA has higher water demand, and the strength of mortar is compromised by this factor. As of today, our research is still ongoing, and we expect to publish more data on different aspects of durability of proposed GGBFS-HCFA binder later.

Reactivity of Fine Quartz in Presence of Silica Fume and Slag

Dune sand is a very abundant material in south of Algeria. Its high silica content gives a partial pozzolanic reactivity due to its crystalline state. This paper investigates the evolution of cement hydration based on a binary addition particularly the reactivity of dune sand finely ground in the presence of an amorphous addition: silica fume or blast furnace slag. Thus, four combinations of binary additions by substitution have been chosen. The X-ray diffraction analyses performed on cement pastes containing additions have shown the importance of the mineralogy and silica content of additions on their pozzolanic reactivity. Dune sand becomes reactive at long term, especially when associated up to 10% of amorphous addition (blast furnace slag or silica fume). It results an increasing in mechanical strength of Ultra High Performance Concrete (UHPC) and an improvement of the microstructure.

Optimum Level of Replacement Slag in OPC-Slag Mortars

The present paper reports the testing of 14 OPC-slag mortars and 2 controls OPC and slag mortars. The main aim is to determine the optimum level of replacement slag for achievement to the highest early strength with reasonable flow. Variable was the level of GGBFS in the binder. In this experimental work, two types of sands were used that are： silica and mining sands. It is determined that the optimum level of replacement slag is 40% and use of silica sand in OPC is preferable to mining sand and reversely, use of mining sand is preferred in GG100 to silica sand. All mortars had W/B and S/B 0.33 and 2.25, respectively.

Shrinkage Behavior of High Performance Concrete at Different Elevated Temperatures under Different Sealing Conditions

The shrinkage behavior of high performance cement concrete made from Portland cement, ultra fine granulated blast furnace slag and pulverized fly ash with addition of superplasticizer at different temperatures from ambient temperature to 120 ℃ under different seuliug conditions was investigated by means of length change measurement on cylindrical concrete specimens along with curing age. Results show that drying shrinkage deformations of titled concrete specimens increased rapidly as the curing temperature rose. The development of dryiing shrinkage deformatian can be efficiently controlled with the aid of aluminum tape sealing as compared with the unsealed specimens, especially when the curing temperature is below 60℃ , although it will increase dramatically when the curing temperature is elevated to above 90%＂ . Polymer coating on concrete specimens showed a similar effect on the control of drying shrinkage as the sealing operation with aluminum tape.

钛渣熔体结构及传输性质分子动力学模拟研究进展

高品位钛渣(TiO_(2)含量≥90%)的高效制备不仅是高品质钛产品生产的关键,而且已成为我国钛冶金行业发展的迫切需要。钛铁矿还原熔炼过程钛渣熔体传输性质的调控是实现高品位钛渣高效制备的关键。国内外学者采用分子动力学模拟的方法,开展钛渣熔体结构演变及传输性质的研究,取得了显著的进展,证实了分子动力学模拟的方法在钛渣熔体研究中的有效性。分子动力学模拟的方法在研究钛渣熔体结构和性质方面具有显著的优势,不但能考察钛渣熔体结构参数、传输性质及相关微观细节,而且不受试验条件(高温、高腐蚀性、高化学活性)的限制。通过分子动力学模拟能够获取钛渣熔体丰富的结构信息和重要的传输性质,避免了钛渣熔体结构及物理性质试验测试中存在的难题。最后,结合冶金熔体成分和结构的复杂性,总结存在的问题,对分子动力学模拟在熔体结构及传输性质研究中的应用进行了展望。

粒化高炉矿渣粉沥青混合料路用性能研究

为了拓宽废弃粒化高炉矿渣的利用途径,文中采用不同比例的粒化高炉矿渣粉代替矿粉后,进行AC-13C沥青混合料配合比设计,并对其高温稳定性、水稳定性和低温抗裂性等路用性能进行对比分析。结果表明,将粒化高炉矿渣粉作为填料应用于沥青混合料中,提高了沥青混合料的高温稳定性和高温水稳定性,但降低了其低温水稳定性。当粒化高炉矿渣粉替代率不超过50%时,沥青混合料的低温抗裂性可以得到提高,而当粒化高炉矿渣粉替代率超过75%时,沥青混合料的低温抗裂性降低。综合分析结论得出,AC-13C沥青混合料的粒化高炉矿渣粉替代率不超过50%。

钢渣粉对高强混凝土力学性能和耐久性的影响

超细矿渣是制备高强混凝土的优质矿物掺合料,但是超细矿渣水化放热量较大、凝结较快,不利于高强混凝土的强度和耐久性发展。而钢渣粉具有延缓水泥水化、降低水化放热的作用,可以充当“缓凝剂”。通过在高强混凝土中复掺钢渣粉和超细矿渣,研究了钢渣粉对高强混凝土性能的影响。结果表明复掺15%钢渣粉时初凝时间和终凝时间分别比纯水泥组延长53.0%和35.9%。同时早期强度降低,但与超细矿渣复掺后28 d和90 d强度分别为77.3 MPa和84.6 MPa,比对照组高4.3%和8.6%。此外,钢渣粉有效降低了高强混凝土的绝热温升和自收缩率。单掺15%超细矿渣时7 d自收缩率为1189.63×10^(-6),约为纯水泥组的2.5倍;复掺15%钢渣粉时自收缩率为211.62×10^(-6),比纯水泥组降低了52%。复掺钢渣粉的高强混凝土与纯水泥制备的混凝土的抗氯离子渗透性等级均为“低”。

水淬高炉矿渣还原性对高硫尾砂氧化过程的影响探索研究

尾砂是选矿厂在特定的经济技术条件下,将矿石磨细,选取有用成分后排放的废弃物,是我国排放量最大的工业固废。尾砂的大量堆存不仅会形成安全隐患,还会引起占用土地、污染土地和水体等问题。利用尾砂进行矿山充填是实现尾砂大宗量消纳处置的有效途径。高硫尾砂一般指硫元素含量大于8%的尾砂,由于高硫尾砂氧化生成的硫酸根达到一定浓度后就会对水泥的硬化过程有破坏作用,导致高硫尾砂在矿山充填中的利用率较低。找到抑制高硫尾砂氧化的方法是降低高硫尾砂环境污染、提高高硫尾砂充填利用率的途径之一。本文通过开展高硫尾砂氧化试验,对水淬高炉矿渣的还原性对高硫尾砂氧化过程的影响开展了探索研究,通过观察试验结果,结合理论分析和其他学者的研究成果,可以得出结论:①高硫尾砂在水中可以发生氧化反应,主要反应过程为黄铁矿(FeS2)等硫化物与水和水中的溶氧反应生成硫酸根和氢离子;②矿渣微粉对高硫尾砂的氧化过程有抑制作用,可以显著减缓水中高硫尾砂的氧化速率;③矿渣微粉具有还原性,还原性来源是高炉中的还原性气氛,还原性的物质承担者是其中低价态的硫;④矿渣微粉抑制高硫尾砂氧化速率的原因是矿渣中低价态的硫优先与水中的溶氧发生反应,降低了高硫尾砂中硫化物的氧化速率。

Effects of MgO/Al_(2)O_(3)and CaO/SiO_(2)ratios on viscosity of high titaniumbearing blast furnace slag

The effects of MgO/Al_(2)O_(3)and CaO/SiO_(2)ratios on the viscosity,break-point temperature,and viscous activation energy of a high titanium-bearing slag were studied.The results showed that both the viscosity and the break-point temperature of the slag decreased with the MgO/Al_(2)O_(3)ratio increasing from 0.50 to 0.65,the viscous activation energy decreased gradually,and the thermal stability became better.In addition,with an increase in CaO/SiO_(2)ratio from 1.12 to 1.22,the main viscous units in the slag depolymerized and the viscosity of slag decreased.However,the break-point temperature of slag showed an increasing tendency.The viscous activation energy decreased gradually and the thermal stability became better.The basic phase in the experimental high titanium-bearing slag was pyroxene,and its amount increased with increasing the MgO/Al_(2)O_(3)ratio while decreased with increasing the CaO/SiO_(2)ratio.

炉渣成分对含钛高铝型高炉渣结构及黏度的影响

为了保证含钛高铝型铁矿石高炉冶炼的稳态顺行,围绕含钛高铝型高炉渣系,解析了炉渣成分、炉渣结构和炉渣黏度之间的内在作用机制.结果表明:当w(TiO_(2))=0~10%时,TiO_(2)呈现酸性氧化物的特性,故随着w(TiO_(2))的增加,炉渣发生聚合反应,黏度增大;当w(TiO_(2))=10%~25%时,随着w(TiO_(2))的增加,(SiO_(4)^(4-)+TiO_(4)^(4-))和AlO_(4)^(5-)的峰谱强度逐渐降低,且(SiO_(4)^(4-)+TiO_(4)^(4-))峰左移,这说明此时TiO_(2)呈现碱性氧化物的特性,炉渣中网状结构被破坏,炉渣发生解聚反应,黏度减小;随着w(Al_(2)O_(3))的增加,AlO_(4)^(5-)的峰谱强度逐渐升高,炉渣中AlO_(4)^(5-)网状结构增加,炉渣发生聚合反应,黏度逐渐增大;随着w(MgO)/w(Al_(2)O_(3))和w(CaO)/w(SiO_(2))的增大,AlO_(4)^(5-)和SiO_(4)^(4-)的峰谱强度降低,炉渣中AlO_(4)^(5-)和SiO_(4)^(4-)网状结构减少,炉渣发生解聚反应,黏度逐渐减小.

汉钢1号高炉强化炉前管理生产实践

通过汉钢1号高炉在钢铁市场持续低迷条件下,原燃料条件持续恶化的情况下,采取高效的管理模式、合理的出铁制度、零间隔出铁、精准控制打泥量、设备智能化技术革新等强化炉前渣铁排放措施,确保及时出净渣铁,使炉前渣铁排放工作满足生产组织的需要,为高炉炉况稳定顺行提供保障,在入炉矿石综合品位低于56.0%的条件下,日平均产量稳定在3800 t以上。