Selective separation and recovery of iron and tin from high calcium type tin- and iron-bearing tailings using magnetizing roasting followed by magnetic separation

In this study, a process of magnetizing roasting followed by magnetic separation, which is used to separate or recover tin and iron from the high calcium type tin- and iron-bearing tailings (containing 35.53 wt.% Fe and 0.56 wt.% Sn), was investigated . A magnetic concentrate containing 66.3 wt.% Fe and 0.07 wt.% Sn with an iron recovery rate of 92.9 wt.% was obtained under optimal conditions: anthracite ratio of 2.5:100, roasting temperature of 850°C, roasting time of 30 min, grinding time of 10 min, and magnetic field intensity of 0.1 T. In addition, the effect of roasting parameters on the separation of iron and tin and phase transformation of SnO₂ was investigated by using X-ray powder diffraction, Scanning Electron Microscopy–Energy Dispersive Spectroscopy, etc.     

Babassu Oil (Orbynia phalerata), an Artisanal Product: Process Optimization of Seed Roasting on Yield,Phenolic Compounds,and Antioxidant Capacity

Babassu oil has high concentrations of phenolic compounds. When seeds are preheated, these compounds tend to migrate to the oil depending on the degree of roasting applied. This study aims to optimize the roasting conditions of babassu seeds using response surface methodology (RSM) and the desirability functions. A central composite rotational design (CCRD) is employed to investigate the effects of two independent variables, temperature (X₁) and roasting time (X₂) which significantly affected response variables, namely yield (%), total phenolics content (TPC), number of phenolic compounds, oxygen radical absorbance capacity, acid value and peroxide value. The quadratic model is adjusted for most responses. The roasting temperature of 222 °C and the roasting time of 43 min are standardized as ideal conditions. Thus, the oil produced at the optimized conditions shows a yield of 54.47% and TPC of 91.53 mg GAE/100 g. In the control oil sample, the presence of phenolic compounds analyzed by HPLC-DAD is not observed while under optimized conditions, seven phenolic compounds are observed. The model of optimized conditions shows a good correlation between the predicted and experimental values. In general, these results demonstrate the effectiveness of optimum roasting conditions in improving the quality of bioactive compounds in babassu oil. Practical Applications : This work aims to optimize the babassu seeds roasting process to obtain oil with a greater number of phenolic compounds and better antioxidant capacity. As the first study on babassu seeds roasting, it contributes to the generation of important data in relation to the identification and quantification of phenolic compounds in the oil. Finally, the optimum roasting conditions established in this work can be explored commercially in babassu oil extraction.     

Separation and recovery of iron and manganese from high-iron manganese oxide ores by reduction roasting and magnetic separation technique

Sodium salts were used in the reduction roasting and magnetic separation process to separate and recover iron and manganese from the high-iron manganese oxide ores to utilize the complex ores. Results showed that Na₂S₂O₃ was the most effective salt. A magnetic concentrate with 86.39 wt% TFe and 96.21 wt% Fe recovery as well as a nonmagnetic product with 54.84 wt% TMn and 85.96 wt% Mn recovery was obtained when the ore sample was reduced at 1100°C for 100 min in the presence of 7 wt% Na₂S₂O₃. In addition, the effects of roasting and separation parameters on the recovery of manganese and iron and the function mechanism of Na₂S₂O₃ were investigated.     

菱铁矿磁化焙烧与磁选分离制备铁精矿

对国内某地菱铁矿进行无还原剂全粒级磁化焙烧-磁选研究. 结果表明,菱铁矿在无还原剂条件下于800℃焙烧15 min,所得焙烧矿在磨矿粒度小于0.074 mm占90%、磁场强度0.10 T条件下磁选,得到铁品位63.15%、铁回收率92.52%的铁精矿. 磁选精矿中的锰、镁和部分钙与铁元素以类质同像共存.     

回收高炉尘泥中的铁与锌

利用高炉尘泥以还原焙烧-磁选工艺获得高品位富铁矿,由醋酸回收液回收还原后的锌得到高纯度醋酸锌产品. 研究得出合理的焙烧工艺条件是：温度1373.2 K、时间60 min. 通过还原焙烧,高炉尘泥脱锌率可达98%,并得到含锌率仅为0.04%(w)、金属化率高的还原矿. 还原矿在150 mT的磁场强度下弱磁选可得铁品位在80%左右的富铁矿,回收液经浓缩结晶后得到纯度达98.7%的醋酸锌副产品. 所得富铁矿和醋酸锌可工业应用.     

Determination of the Optimum Conditions for Copper Leaching from Chalcopyrite Concentrate Ore Using Taguchi Method

The optimum conditions for the extraction of copper from chalcopyrite concentrate into SO₂-saturated water were evaluated using the Taguchi optimization method. High level copper recovery was obtained in an environmentally friendly process that avoids sulfur dioxide emission into the atmosphere because SO₂ forming in the roasting is used in the dissolution. Experimental parameters and their ranges were chosen as follows: reaction temperature, 293–333 K; solid-to-liquid ratio, 0.025–0.15 g/mL; roasting time, 30–90 min; roasting temperature, 773–973 K; stirring speed, 400–800 rpm; and reaction time, 10–60 min. The particle size and gas flow rate were 63 µm and 10 cm³/min, respectively. The optimum conditions of the dissolution process were determined to be reaction temperature of 318 K, a solid-to-liquid ratio of 0.025 g mL^?1, a roasting time of 75 min, a roasting temperature of 773 K, a stirring speed of 400 rpm, and a reaction time of 30 min. Under optimum conditions, dissolution yield of copper was 91%.     

生物质还原磁化褐铁矿的实验研究

研究了广西崇左褐铁矿磁性转化和还原机理. 通过生物质与褐煤焙烧还原褐铁矿的对比实验,考察了焙烧温度、焙烧时间、原料配比等工艺条件对矿物磁性的影响. 结果表明,生物质还原的最佳焙烧温度为650℃左右,焙烧时间30 min,生物质用量为15%~20%. 结合XRD分析结果,确定以褐煤及生物质还原铁矿主要得到磁性Fe3O4及g-Fe2O3,温度高时易转化成硅酸铁,影响后续磁选回收铁.     

Chemometric study of thermal treatment effect on the P25 photoactivity for degradation of tartrazine yellow dye

In the present work, a chemometric study was carried out using a central composite rotatable design (CCRD) to evaluate the effect of thermal treatment on the P25 photoactivity for degradation of tartrazine dye. The factors investigated for thermal treatment were: temperature, heating rate and heating time, and the experimental design response was the photodegradation constant (k_app). The response surface methodology (RSM) was employed to obtain the material with higher k_app value for tartrazine photodegradation, under UV radiation, and investigate the interactions between factors of thermal treatment. The P25 used as precursor, as well as the obtained material from the optimized conditions (TTP_op), and the material with worst photocatalytic activity (TTP-17) were characterized from the N₂ physiosorption, FT-IR, SEM, XRD, DSC/TGA and PAS. The TTP_op was obtained under conditions of temperature of 298?°C, heating rate of 10?°C?min^?1 and heating time of 177?min. TTP_op showed k_app value of 25.7, while P25 and TTP-17 presented k_app values of 20.2 and 10.0, respectively.     

Separation and recovery of iron from a low-grade carbonate-bearing iron ore using magnetizing roasting followed by magnetic separation

In this study, a process of magnetizing roasting followed by low-intensity magnetic separation (MR-LMS), which is used to separate and recover iron from a low-grade carbonate-bearing iron ore (containing 34.6 wt.% Fe), was investigated. A magnetic concentrate containing 65.4 wt.% Fe with an iron recovery rate of 92.6 wt.% was obtained under optimal conditions: roasting temperature of 800°C, roasting time of 8 min, bitumite ratio of 10:100, grinding fineness of around 85 wt.% passing 38 µm, and magnetic intensity of 0.12 T. In addition, the phase transformation and magnetic properties were analyzed by X-ray diffraction (XRD) and vibrating sample magnetometry (VSM) to reveal the mechanism.     

The effect of the calcination temperature of LaFeO3 precursors on the properties and catalytic activity of perovskite in methane oxidation

In the synthesis of perovskite-type LaFeO₃ oxides iron and lanthanum nitrates were used as a precursors. The nitrates were dissolved in water, evaporated, crushed and calcined in temperature range of 650–850?°C. The obtained perovskites were applied as an active layer on monolithic catalysts for the oxidation of methane. The increase in the calcination temperature of the perovskite precursors from 650° to 850°C results in a reduction in the surface area of the powders from 10.1 to 4.2?m²/g. XRD studies revealed that calcination at 800–850?°C caused the formation of an almost homogeneous LaFeO₃ perovskite phase. A decrease in the La/Fe surface ratio from 12 to 5.2 with the rise in calcination temperature from 650° to 800°C was detected by XPS. EDX results confirmed that at 750–850?°C, the La/Fe ratio in the perovskite layer is close to the stoichiometric and amount to 1.01–1.03. The highest activity in methane oxidation was achieved when the LaFeO₃ perovskite was calcined at 700?°C. A further slight increase in the activity was noticed after H₂ treatment. As the calcination temperature of the perovskites is increased, the catalyst activity decreases due to a reduction in the specific surface area, despite the more complete LaFeO₃ perovskite phase formation.     

Promoted Fe/ZSM-5 catalysts prepared by sublimation: de-NOx activity and durability in H2O-rich streams

Fe/ZSM-5 catalysts with an Fe/Al ratio 1:0, were prepared by sublimation of FeCl3 into H/ZSM-5. They display high activity and durability for the selective catalytic reduction of NOx to N2, both in dry and wet gas flows. These catalysts have now been modified by exchanging a second cation into the zeolite. Mere neutralization of zeolite protons by Na⁺ lowers the selectivity for NOx reduction to N2, but the cations Ce₃ ⁺ and La₃ ⁺ act as true catalyst promoters. With isobutane as the reductant in a simulated vehicular emission gas, almost 90% of NOx is reduced to N2 at 350°C over the La-promoted catalyst. The presence of 10% H2O in the feed does not impair the catalyst performance at high temperature; in the temperature region below 350°C it even increases the N2 yield. The beneficial effect of La is due to its lowering of the catalyst activity for the undesired combustion of the hydrocarbon. No signs of zeolite destruction are evident after 100 h TOS in a wet gas flow at 350°C. Carbonaceous deposits causing a slight deactivation are easily removed in an O2/He flow at 500°C; this in situ regeneration fully restores the original activity. This revised version was published online in July 2006 with corrections to the Cover Date.     

Separation and recovery of neodymium and praseodymium from permanent magnet scrap through the hydrometallurgical route

The leaching of neodymium (Nd) and praseodymium from scrap permanent magnet bearing 64.37% Fe, 30.57% Nd and 0.42% Pr and 0.71% B was carried out using HCl solution. X-ray fluorescence (XRF) and X-ray diffraction (XRD) analyses study ensured the elements of the above metals as Nd-Fe-B in the solid phase . The leaching parameters – HCl concentration, time, temperature, particle size, pulp density (S/L) – were investigated to obtain the suitable leaching condition for the effective dissolution of both Nd and Pr. At the conditions of 0.2 M HCl, temperature 90°C, leaching time 240 min, particle size 76–105 µm, agitation speed 800 rpm and pulp density (PD) 1%, the leaching efficiencies of Nd and Fe were 99.99% and 61.36%, respectively. The optimum leaching condition was established by minimizing iron co-extraction vis-à-vis the quantitative recovery of Nd and Pr. The iron content of the leach liquor was removed by the precipitation method using lime (Ca(OH)₂) at pH 4.0. After the removal of iron, the solvent extraction (SX) parameters were optimized and the McCabe–Thiele diagram for extraction and stripping was developed. The McCabe–Thiele plot for extraction with 0.8 M NaD2EHPA (30% neutralized) and stripping with 8% H₂SO₄ showed two stages at A:O = 2:1 and O: A = 4:1, respectively, for the quantitative recovery of Nd and Pr. The final strip solution bearing 72 g/L Nd and 1.088 g/L Pr was crystallized to produce (Nd) ₂(SO₄)₃ and (Pr) ₂(SO₄)₃, respectively.     

Preparation and characterisation of TiN by microwave-assisted carbothermic reduction–nitridation in air atmosphere

Titanium nitride (TiN) is prepared from ilmenite (FeTiO₃) powders by microwave-assisted carbothermic reduction–nitridation in air atmosphere followed by acid leaching treatment. The thermal analysis of the reduction–nitridation of FeTiO₃ powders is conducted by thermogravimetry/differential scanning calorimeter. The phase transition sequence of microwave carbothermal synthesis of TiN–Fe composite is: FeTiO₃?→?Fe?+?TiO₂?→?Fe?+?TiN. There is no any other oxygen-deficient titanium oxides detected. Particularly, FeTiO₃ can be transformed into TiN–Fe composite completely at 900°C for 60?min by microwave heating. The increase in both the reaction temperature and dwelling time is in favour of the transformation of FeTiO₃. The product morphologies are spherical about 2–5?μm in size. Then TiN is obtained with the removal of Fe and their oxides from TiN–Fe composite by acid leaching treatment. This method not only reduces the reaction temperature significantly through microwave heating but also can simplify the operation process effectively.     

Effect of Glucose on the Synthesis of Iron Carbide Nanoparticles from Combustion Synthesis Precursors

Iron carbide (Fe₃C) nanoparticles have been successfully synthesized by combining low‐temperature combustion synthesis method with carbothermal reduction. A homogeneous precursor powder (Fe₂O₃ + C) derived from iron nitrate, glycine, and glucose mixed solution was subsequently calcined under nitrogen at 450°C–700°C for 2 h. Effects of glucose on the size and morphology of the precursors as well as the synthesized Fe₃C powders were studied in details. The results showed a regular variation in the particle size and morphology of the precursors and Fe₃C powders with the increasing molar ratio of glucose to iron nitrate (G/Fe). XRD analysis indicated that the initial transformation of the precursor for (G/Fe = 1) to Fe₃C occurred at 500°C. Meanwhile, magnetic properties of the Fe₃C have been tested by vibrating sample magnetometer (VSM). The saturation magnetization (Ms) of Fe₃C powders synthesized using different G/Fe ratios (G/Fe = 1, 2, 3) was 51.2, 37.0, and 27.1 emu/g, respectively. This made the Fe₃C a promising candidate for magnetic materials.     

Transformations of Iron (III) Precursors in a Wave of Flameless RDX Combustion

Flameless combustion of 40% Fe₂O₃ – 40% RDX – 20% HDI (mix I) and 30% CoCO₃ – 15% iron formate – 40% RDX – 15% HDI (mix II) systems was explored by time-resolved X-ray diffraction (TRXRD). In case of mix I, the reaction was found to proceed via the formation of FeO intermediate: Fe₂O₃ → FeO → Fe₃O₄. Variation in the extent of iron reduction was associated with dynamic temperature change and a reductant content of the reaction zone. The reduction proceeded as a solid-state reaction, without amorphization of the structure. The process in system II involved the formation of CoO and FeO intermediates. Further reduction – up to metals – takes place behind the combustion front and yields a mixture of nanosized Co, Fe, and Co_0.7Fe_0.3 particles. Exposure of hot reaction products – nano-sized Co and Fe – to the air leads to their self-ignition and formation of Co₃O₄ and Fe₃O₄, respectively.     

Optimization of transglutaminase extraction produced by Bacillus circulans BL32 on solid‐state cultivation

BACKGROUND: This paper reports investigations of the extraction of transglutaminase (TGase) produced by Bacillus circulans BL32 on solid‐state cultivation in order to obtain a crude extract with the highest possible specific activity. The optimization of downstream processing parameters for the effective recovery of the enzyme was carried out using response surface methodology based on the central composite rotatable design (CCRD) to reduce losses in the cultivated solids and to obtain a crude extract as concentrated as possible. Several solvents and temperatures were tested, followed by a 2³ factorial design performed to optimize conditions extraction time, mechanical agitation, and solid:liquid ratio. RESULTS: The mathematical model showed that solid:liquid ratio has a significant negative effect on transglutaminase recovery. The optimal conditions for extraction were: water as solvent at 7 °C; 5 min extraction time; agitation speed 250 rpm; and 1:6 solid:liquid ratio. Under these conditions the model predicts a maximum response of 0.291 U mg^?1 of protein of transglutaminase activity recovery, very closely matching experimental activity of 0.285 U mg^?1 of protein. TGase recovery achieved under the optimized extraction conditions, according to the CCRD, was 2.5‐fold higher than that obtained under non‐optimized conditions previously employed. CONCLUSION: Results show that TGase can be produced in cheap solid state cultivations and the optimization of its downstream processing parameters can improve enzyme recovery in crude extracts and may have important impacts on enzyme costs. Copyright © 2008 Society of Chemical Industry     

生物质还原-磁选不锈钢酸洗污泥

以生物质为还原剂,通过还原?磁选实验考察了还原温度、生物质种类和添加量、磁场强度及磁选粒度对回收酸洗污泥中铁的影响。结果表明,在反应温度为700℃、棉花秸秆添加量为5wt%、还原产物破碎至粒度小于0.074 mm颗粒占70%、磁场强度为200 mT条件下磁选回收,所得产物中铁品位为67.72wt%、回收率达91.83%。     

INCREASE IN PHYTASE SYNTHESIS DURING CITRIC PULP FERMENTATION

Citric pulp bran was used for the first time as substrate for phytase synthesis under solid-state fermentation. An A. niger FS3 phytase strain was applied in optimization studies. A Plackett-Burman screening design identified significant physicochemical variables. These preselected variables were subsequently optimized using a central composite rotational design (CCRD). The maximum phytase production was achieved with the following optimum variables: 30°C temperature, 65% initial moisture content, 0.3 M Na-citrate buffer concentration, initial pH 5.0, and 1.5% urea concentration. An overall 4.3-fold improvement in phytase production was successfully achieved.     

OPTIMIZATION OF LIPASE-CATALYZED SYNTHESIS OF N-trans-FERULOYLTYRAMINE USING RESPONSE SURFACE METHODOLOGY (RSM)

Enzymatic synthesis of N-trans-feruloyltyramine amide was optimized by response surface methodology (RSM) using 4-hydroxy-3-methoxycinnamic acid and tyramine hydrochloride in a one-step lipase catalyzed reaction using Lipozyme TL IM. Response surface methodology (RSM) based on five-level, four-variable central composite rotatable design (CCRD) was used to evaluate the interaction of synthesis, reaction time (24–96 h), temperature (30°–50°C), amount of enzyme (50–500 mg, 12.5–125.0 IUN), and substrate molar ratio (cinnamic acid:tyramine HCl) 1:1–8:1 mmol on the percentage yield of N-trans-feruloyltyramine amide. The optimum conditions derived via RSM were: reaction time 52 h, temperature 43°C, amount of enzyme 260 mg (65.0 IUN), and substrate molar ratio (cinnamic acid:tyramine HCl) 6.2:1. The actual experimental yield was 96.3% under optimum conditions, which compared well to the maximum predicted value of 97.2%.     

Thermodynamic studies on sulphate roasting for zinc electrowinning from carbonate ore

The bulk of the work consists of a theoretical study of the possibility of submitting Umm-Gheig carbonate ore to sulphate roasting. The use of the admixture with pyrites is to enable a carbonate ore to be treated in a similar way to a sulphide ore, and by doing so, to produce a roasted product capable of being treated by orthodox zinc electrowinning methods using sulphate solutions. Thermodynamic studies have been made to find the optimum conditions for sulphate roasting, in either normal air or enriched 36% oxygen air. The results obtained from the experimental work at different roasting temperatures in a tube furnace indicated that a maximum dissolution of 91.2% Zn with a 17.9% Fe could be obtained at a roasting temperature of 650°C for 4 h, followed by leaching in 4% H₂SO₄ (by vol.) at 60°C. The results of the electron microscopic investigation confirmed by metal value data given in the ASTM cards coincide well with results given by chemical analysis.