Search

In order to explore the potential application of oily sludge-based pyrolysis residue in the treatment of wastewater with phosphate and fluoride, batch adsorption experiments were carried out using the pyrolysis residue with porous structure as an adsorption material. The effects of the residue dosage and initial concentration of phosphate and fluoride on adsorption removal efficiency, as well as adsorption kinetics and isotherms were determined experimentally. The adsorption mechanism was discussed using the techniques of SEM-EDS, XRD, FTIR and Zeta potential test. The results showed that both phosphate and fluoride in aqueous solution can be significantly adsorbed and removed by pyrolysis residue. The adsorption isotherms can be simulated well by Langmuir equation, and the qmax of phosphate and fluoride on the pyrolysis residue were 36.72 and 37.27 mg/g, respectively. The kinetics can be fitted well by the pseudo-second order kinetic equation, showing that the adsorption mechanisms of phosphate and fluoride on pyrolysis residue were chemisorption, and the adsorption rate was controlled by the internal diffusion. The adsorption removal of phosphate and fluoride were due to the formation of CaHPO4·2H2O, Ca3(PO4)2 and CaF2 precipitate on the pyrolysis residue surface. The pyrolysis residue has been proved to be a promising candidate for the removal of phosphate and fluoride from aqueous solution.

Pyrolysis residue, with the porous structure similar to activated carbon, was proposed as a material to remove heavy metals with low levels from synthetic flotation wastewater in the work. The effects of the dosage on removal efficiency, adsorption kinetics and isotherms were studied. The adsorption mechanism was also discussed. The results showed that pyrolysis residue could remove effectively Cd2+, Pb2+ and Cu2+ from the flotation solution and increase simultaneously its effluent pH. The removal efficiency of Cd2+, Pb2+ and Cu2+ was 99.3, 98.9 and 99.4%, and the corresponding solution pH was 9.79, 9.12 and 8.45 when pyrolysis residue dosages was 1, 0.8 and 0.8 g/L with same 20 mg/L concentrations of Cd2+, Pb2+ and Cu2+ and natural synthetic solution pH, respectively. The pseudo-second-order rate constant (k2) and the qmax of Cd2+, Pb2+and Cu2+ were 0.05, 0.03, 0.04 g/(mg·min) and 106.16, 140.65, 128.04 mg/g. Heavy metals was mainly removed by formation of stable metal sulfides and hydroxides on the surface. The above results have uncovered that pyrolysis residue was viable for removal of heavy metals with low levels from flotation wastewater for the first time.

This paper provides a technical approach for efficiently recovering Mg from ferronickel slag to produce high-quality magnesium oxide (MgO) by using the sulfuric acid leaching method under atmospheric pressure. The leaching rate of magnesium is 84.97% after a typical one-step acid leaching process, which is because Mg in FNS mainly exists in the forsterite (Mg2SiO4) phase, which is chemically stable. In order to increase the leaching rate, a two-step acid leaching process was proposed in this work, and the overall leaching rate reached up to 95.82% under optimized conditions. The response surface methodology analysis for parameter optimization and Mg leaching rules revealed that temperature was the most critical factor affecting the Mg leaching rate when the sulfuric acid concentration was higher than 2 mol/L, followed by acid leaching time. Furthermore, interactive behavior also existed between the leaching temperature and leaching time. The leaching kinetics of magnesium from FNS followed a shrinkage-nuclear-reaction model with composite control, which were chemically controlled at lower temperatures and diffusion controlled at higher temperatures; the corresponding apparent activation energy was 19.57 kJ/mol. The leachate can be used to obtain spherical-like alkali magnesium carbonate particles with diameters of 5–10 μm at 97.62% purity. By using a further calcination process, the basic magnesium carbonate can be converted into a light magnesium oxide powder with a particle size of 2–5 μm (MgO content 94.85%), which can fulfill first-level quality standards for industrial magnesium oxide in China.

The carbonaceous material (CM) prepared by refinery oily sludge was proposed to remove flotation collectors, butyl xanthate (BX), and diethyldithiocarbamate (DDTC) in synthetic wastewater. The effects of the CM on removal efficiency, adsorption kinetics, and isotherms were experimentally carried out. The surface structure and composition of CM were characterized by BET isotherm, XRD, and SEM-EDS, and the concentration of BX and DDTC was tested by UV-VIS spectrometer. The adsorption behavior and removal mechanism were investigated by zeta potential, ToF-SIMS, FTIR, etc. The removal efficiencies of BX and DDTC were both more than 99%, and the maximum adsorption capacity peaked when the pH of the solution was neutral. The two collectors were heterogeneous adsorption on the surface of CM. BX, DDTC, and related metal compounds were found on the surface of carbonaceous material, confirming the existence of both physical and chemical adsorption, and physical adsorption accounted for the main mechanism. It is proved that BX and DDTC can be removed by carbonaceous material and realize the high-effective utilization of refinery oily sludge.

To dispose of arsenic-containing tailings with low carbon and high efficiency, sodium sulphate (Na2SO4), sodium hydroxide (NaOH), calcium nitrate Ca(NO3)2 and calcium hydroxide Ca(OH)2 were independently added to metallurgical slag-based binder (MSB) solidification/stabilisation (S/S)-treated tailings (MSTs) to enhance the MST arsenic S/S performance. Results showed that only Ca(OH)2 could increase the unconfined compressive strength of MST from 16.3 to 20.49 MPa and decrease the leachate As concentration from 31 μg/L to below 10 μg/L. Na3AsO4·12H2O and NaAsO2 were used to prepare pure MSB paste for mechanism analysis. The results of microstructure analyses showed the high specific surface area and amorphous properties of calcium–sodium aluminosilicate hydrate facilitated the adsorption or solid-solution formation of As(V) and As(III). As(V) formed an inner-sphere complex in ettringite, whereas As(III) formed an outer-sphere complex, and the relatively larger size and charge of As(V) compared with SO42− restrict substitution inside channels without affecting the ettringite structure under high loading of As(V). The added Ca(OH)2 promoted the hydration reaction of MSBs and facilitated the formation of a Ca–As(V) precipitate with low solubility, from Ca4(OH)2(AsO4)2·4H2O (Ksp = 10−27.49) to Ca5(AsO4)3(OH) (Ksp = 10−40.12). This work is beneficial for the application of cement-free MSB in the S/S process.

The current study investigated the efficiency and mechanisms of in situ immobilization of artificially Cd-contaminated soils with ferronickel slag (FNS). The available Cd content of soil was measured and the modified European Community Bureau of Reference (BCR) sequential extraction procedure (SEP) was adopted to quantify the evolutions of Cd chemical speciation after the immobilization by the FNS. The results showed that the addition of FNS (5%‒15%) remarkably reduced the available Cd content and increased the pH and cation exchange capacity of soils. The passivation rate of Cd increased from 58.13% to 73.25% as the spiked Cd content rose from 10 to 120 mg kg‒1. The BCR SEP test revealed that the FNS addition substantially reduced the acid soluble fraction and increased the residual fraction of Cd, indicating the reduction of mobility and bioavailability of Cd in soils. The chemical precipitation, ion exchange and surface complexation might be involved in in situ immobilization of Cd-contaminated soils by the FNS.

In this paper, a new method for the comprehensive recovery and recycle of jarosite residues (JR) is proposed. By direct reduction followed by magnetic separation, lead, zinc and iron are separated and recovered from JR and sulfur is fixed. The non-magnetic tails (NMT) of the magnetic separation is used for removing of Cd, As and Pb heavy metal ions from acidic wastewater of zinc hydrometallurgy. Test work results showed that the volatilization rates of lead and zinc were 96.97% and 99.89%, respectively, the sulfur fixation rate with CaO was 98.91% under optimal conditions of reduced roasting at 1523 K for 60 min. A magnetic iron concentrate was obtained containing 95.68% iron at a recovery of 76.26% by grinding-magnetic separation process. The removal rates of Cd, As and Pb ions were 99.98%, 93.75% and 99.80% respectively. The content of Cd, As and Pb ions in the treated wastewater met the emission standards at 120 g/L NMT dosage and for a contact time of 90 mins. The proposed method is considered as an environmentally-friendly and efficient approach to the comprehensive recovery and recycle of JR and the removal of toxic cadmium, arsenic and lead ions from acidic wastewater of zinc hydrometallurgy.

Purpose: Chemotherapy is the clinically recommended treatment for patients with operable metaplastic breast carcinoma (MBC); however, its impact remains controversial. This study investigated the possible role of chemotherapy in the treatment of MBC.Methods: The Surveillance, Epidemiology, and End Results (SEER) database was used to identify the operable MBC patients. The competing risk analysis along with the propensity score matching (PSM) method was performed to evaluate the effect of chemotherapy. Moreover, a competing risk nomogram was built to identify prognosis in patients with MBC.Results: Of the 1137 patients with MBC, 775 received chemotherapy and 362 did not receive chemotherapy. The 5-year cumulative incidence of breast cancer-specific death (BCSD) showed similar outcomes in both the Chemo and No-Chemo groups (21.1 vs. 24.3%, p = 0.57). Chemotherapy showed no apparent association with BCSD (HR, 1.07; 95% CI, 0.72–1.60; p = 0.72), even after subgroup analysis or PSM. Race, tumor size, lymph node status, and radiation were identified as the significant factors for MBC after a penalized variable selection process. In addition, a competing risk nomogram showed relatively good accuracy of prediction with a C-index of 0.766 (95% CI, 0.700–0.824).Conclusion: Our findings demonstrated that chemotherapy did not improve BCSD for operable MBC patients. Thus, it may indicate the need to reduce exposure to the current chemotherapy strategies for patients with resectable MBC. Additionally, some novel treatment strategies are required urgently to identify and target the potential biomarkers.

In-site remediation is a relatively promising and socially acceptable technique for heavy metal contaminated soils. But the key task is to select cost-effective and environment-friendly amendents for the consideration of practical application. Based on the property of four typical silicate wastes such as straw ash (SA), coal fly ash (CFA), ferronickel slag (FNS) and blast-furnace slag (BFS), effects of four wastes on available Cd content and Cd chemical speciation in amended soils, and physicochemical properties of the amended soils were carried out in the study. The results showed that four wastes were dominately composed of the amorphous phases with OH− ions readily released. When the weight ratio of silicate wastes to artificial Cd-contaminated soils reached 10%, the available Cd contents decreased from 4.12 mg/kg in untreated soils to 1.94, 1.92, 1.45 and 1.53 mg/kg in amended soils by adding SA, CFA, FNS and BFS respectively, after the soils were amended for 30 days. The residual fraction of Cd (R) was 2.54, 2.48, 2.77 and 2.58 times higher in amended soil than that in untreated soil when SA, CFA, FNS and BFS was added, respentively. The soil pH and CEC were improved. The amended soils by adding SA and FNS were looser than those by adding CFA and BFS, and air permeability of the amended soils by SA was better than that by FNS.

The CaS-containing alkaline slag (CCAS), discharged after recovering valuable metals from high-surfur residues in zinc hydrometallurgical plants, was used to remove heavy metal ions from acid wastewater produced in zinc hydrometallurgical process. The CCAS was capable of effectivly removing aqueous Pb2+ and Cd2+ ions with the neutralization of acid wastewaters. As the CCAS usage was 30 g/L for Pb2+ and 45 g/L for Cd2+ containing synthetic solutions, the removal rate of Pb2+ and Cd2+ reached 99.13% and 99.87% with the equilibrium pH of 10.81 and 10.85, respectively. The Pb2+ and Cd2+ ions were removed with the CCAS by generating metal sulfides, hydroxides and aluminosilicates. The treatment of real acid wastewater from zinc hydrometallurgical process was also investigated with the CCAS. As the CCAS usage was 160 g/L, the concentrations of Cd2+, Pb2+, As3+ and Zn2+ ions were reduced to 0.102 mg/L, 0.09 mg/L, 0.003 mg/L and 0.0193 mg/L respectively, and the equilibrium pH of treated wastewater was increased from around 2.0 to 11.30. For the treatment of real wastewater, heavy metals were proved to be removed by forming Cd2SO4(OH)2, Cd3Al2Si3O12, PbSO4 and CuS on CCAS surface. The results revealed that it was feasible for the CCAS to treat real acid wastewater discharged from zinc hydrometallurgical process. However, the used CCAS must be stored in specialzed landfill because the leaching concentration of Cd2+ reached 0.107 mg/L, which was higher than the Cd2+ emission standard of 0.05 mg/L.

In the present study, the straw ash (SA) was proposed to remove phosphate and fluoride from aqueous solution. The effects of SA dosage, initial contaminants concentration and initial pH on removal efficiency, adsorption kinetics and isotherms were investigated in batch experiments. The removal mechanisms were also discussed. The results show that solution pH was a critical parameter for the adsorption and the removal efficiency decreased with the increase of initial pH. At initial solution pH of 2, the removal efficiency of SA (25 g/L) for phosphate (200 mg/L) achieved 88.20%, and the fluoride (100 mg/L) removal rate by SA (50 g/L) was 87.52%. The adsorption for phosphate/fluoride followed the pseudo‒second‒order kinetic model. The adsorption isotherm data were well fitted by the Langmuir model, and the maximum adsorption capacity of SA reached 92.16 mg/g for phosphate and 66.23 mg/g for fluoride. The SEM-EDS and XRD tests show that phosphate/fluoride were mainly removed by chemically precipitating as CaHPO4, Ca4H(PO4)3·2.5H2O, Ca5(PO4)3(OH) and AlF3, CaF2 on the SA surface. Electrostatic attraction and ligand exchange with hydroxyl groups also exited in the removal process. Besides, SA has been proved to be a promising adsorbent for the treatment of industrial wastewater contaminated with phosphate and fluoride.

Embedding direct reduction followed by magnetic separation was conducted to fully recover iron and titanium separately from beach titanomagnetite (TTM). The influences of reduction conditions, such as molar ratio of C to Fe, reduction time, and reduction temperature, were studied. The results showed that the TTM concentrate was reduced to iron and iron-titanium oxides, depending on the reduction time, and the reduction sequence at 1200 °C was suggested as follows; Fe 2. 75 Ti 0. 25 O 4 →Fe 2 TiO 4 →FeTiO 3 →FeTi 2 O 5 . The reduction temperature played a considerable role in the reduction of TTM concentrates. Increasing temperature from 1100 to 1200 °C was beneficial to recovering titanium and iron, whereas the results deteriorated as temperature increased further. The results of X-ray diffraction and scanning electron microscopy analyses showed that low temperature (≤ 100 °C) was unfavorable for the gasification of reductant, resulting in insufficient reducing atmosphere in the reduction process. The molten phase was formed at high temperatures of 1250–1300 °C, which accelerated the migration rate of metallic particles and suppressed the diffusion of reduction gas, resulting in poor reduction. The optimum conditions for reducing TTM concentrate are as follows: molar ratio of C to Fe of 1. 68, reduction time of 150 min, and reduction temperature of 1200 C. Under these conditions, direct reduction iron powder, assaying 90. 28 mass% TFe and 1. 73 mass% TiO 2 with iron recovery of 90. 85%, and titanium concentrate, assaying 46. 24 mass% TiO 2 with TiO 2 recovery of 91. 15%, were obtained.

The diethyl dithiocarbamate (DDC) collector, a precursor of toxic N-nitrosamines, is detected in flotation wastewaters usually at the ppm level. In this study, the O3 and O3/Vacuum-UV (O3/VUV) processes were compared to investigate the efficient removal of DDC with a low risk of N-nitrosamine formation. The results showed that 99.55% of DDC was removed at 20 min by O3/VUV, and the degradation rate constant was 3.99 times higher than that using O3-alone. The C, S and N mineralization extents of DDC using O3/VUV reached 36.36%, 62.69% and 79.76% at 90 min, respectively. O3/VUV achieved a much higher mineralization extent of DDC than O3-alone. After 90 min of degradation, O3/VUV achieved lower residual concentrations of CS2 and H2S, and released lower amounts of gaseous sulfur byproducts compared to O3-alone. The solid phase extraction and gas chromatography-mass spectrometry (SPE/GC–MS) analysis indicated that the main byproducts in O3/VUV degradation of DDC were amide compounds without the detection of N-nitrosamines. The avoidance of N-nitrosamine formation might be attributed to exposure of UV irradiation and enhanced formation of ˙OH radicals in the O3/VUV system. The degradation pathways of DDC were proposed. This work indicated that O3/VUV was an efficient alternative treatment technique for the removal of DDC flotation collector with low risk of N-nitrosamine formation.

A novel carbonaceous material (NCM), prepared by the pyrolyzation of the oily sludge of tank bottom, was proposed to remove Cr(VI) from a synthetic solution for the first time. The effects of initial Cr(VI) concentration, NCM dosage and initial solution pH on Cr(VI) removal and the adsorption kinetics, the adsorption isothem were investigated. The removal mechanism was studied by comparing the surface properties of NCM before and after the Cr(VI) removal. The results showed that NCM can effectively remove Cr(Ⅵ) from the synthetic solution with the increase of solution pH at equilibrium. At the initial Cr(Ⅵ) concentrations of 40, 100, 150 and 250 mg/L and NCM dosages of 1, 3, 6 and 8 g/L with initial solution pH of 2, the removal efficiency of Cr(VI) was 95.5, 96.8, 95.2 and 81.2%, and the solution pH at equilibrium reached 2.3, 3.5, 5.8 and 7.5, respectively. NCM was suitable for Cr(Ⅵ) removal while the initial Cr(VI) concentration was less than 100 mg/L and initial solution pH was lower than 2.5. Most of Cr(VI) was removed by the reduction of Fe2+ and S2− in NCM to Cr(III) and with the generation of stable FeCr2O4. Some Cr(VI) may be removed by reacting with Fe2+ and Ca2+ to produce CaCrO4 and FeCrO4 on the NCM surface. The dissolution of CaAl2Si2O8 and CaS in the solution increased the solution pH at equilibrium. NCM has been proved to be a material with dual functions both chemical reduction and adsorption.

Physicochemical Problems of Mineral Processing; ISSN 2084-4735

Rationale: Intracystic papillary breast carcinoma is extremely rare in males with a favorable prognosis. Clinical and mammographic manifestations of IPC are not specific, and no consensus has been reached on its management. Patient concerns: Three cases of IPC of the breast in male patients who underwent surgery are presented. In each patient, clinical manifestations, radiological appearance, surgical procedures, pathological diagnosis, and prognosis were investigated. Diagnosis: Ultrasonography showed a complex mass with cystic and nodular solid components in 2 patients and a solid hypoechoic mass in the other 1. Contrast-enhanced ultrasonography(CEUS) was performed for 1 patient demonstrated a solid component of the characteristic enhancement patterns. The final diagnosis of IPC was made after an excisional biopsy. Interventions: A mastectomy with sentinel lymph node mapping was carried out in 2 patients, and it was negative for metastatic disease. The third patient received a mastectomy without an investigation of the axillary lymph node status. Outcomes: All the patients are disease-free during a median follow-up of 67 months (range, 13–120) months. Lessons: It is difficult to diagnose IPC of the male breast before surgery, excisional biopsy is necessary. CEUS can be useful to diagnose IPC in male patients in the preoperative evaluation. Sentinel node biopsy may be considered in patients with IPC associated with DCIS or invasive carcinoma.

Background Pre-treatment serum albumin (ALB) is a novel index that was identified in recent years and is considered to be closely related to the prognosis of nasopharyngeal carcinoma (NPC). However, the association between ALB and NPC remains controversial. Objective of review To assess the prognostic significance of pre-treatment serum ALB in patients with NPC. Type of review A systematic review and meta-analysis. Search strategy We searched PubMed, the Cochrane Library and the Web of Science for studies published up to August 2018. The keywords used were related to albumin, nasopharyngeal carcinoma and prognosis. Evaluation method We extracted the following data from all included studies: author, publication year, country, cancer centre, time points of randomisation, sample size, mean or median age, gender, TNM stage of NPC, cut-off value of pre-treatment serum albumin, number of high-grade cases and duration of follow-up. Then, we generated the pooled hazard ratios (HR) for overall survival (OS) and distant metastasis-free survival (DMFS) to perform this meta-analysis. Results Ten studies comprising 7339 cases were included. Lower pre-treatment serum ALB levels were significantly associated with worse OS (HR = 1.32, 95% CI 1.17-1.48) and DMFS (HR = 1.40, 95% CI 1.08-1.80). In general, our findings were further verified in the subgroup analyses based on three features, including cancer stage, cut-off value and analysis type. Conclusion A decreased level of pre-treatment serum albumin implies a poor prognosis and can be detected to define the risk stratification of NPC patients.

Physicochemical Problems of Mineral Processing; ISSN 2084-4735

The removal of four alkyl xanthates (ethyl, isopropyl, n -butyl and n -amyl) by the O 3 and UV/O 3 processes was investigated in a semi-batch, bubble column reactor. Each alkyl xanthate was almost completely decomposed within 10 min by both the O 3 and UV/O 3 processes, confirmed by UV–vis spectroscopic analysis. However, the mineralization of xanthates was less effective compared to simple decomposition of xanthate molecules. The removal of COD in 40 min was just 50.9–61.2% by O 3 oxidation of four alkyl xanthates, but the removal increased to 66.2–81.2% by the UV/O 3 process. Additionally, the ozone utilization ratio increased by 15–30% by adding UV radiation in the O 3 process. The sulfur mineralization ratio of –CSS − groups of xanthates in 40 min reached approximately 45% and 55% in the O 3 and UV/O 3 processes, respectively, revealing the effective mineralization of sulfur byproducts such as CS 2 , COS and S 2− . The enhancement mechanism of xanthate mineralization and ozone utilization was discussed for the UV/O 3 system. In a weak acid solution, direct oxidation with O 3 was predominant for O 3 process. In contrast, O 3 could be readily decomposed by UV radiation to form reactive radicals in the UV/O 3 process, thus enhancing xanthate mineralization and ozone utilization. Compared to the O 3 process, the UV/O 3 process was more effective in mineralization of xanthates and reduced O 3 consumption.

The alkaline molten-salt method was taken to effectively extract silicon from the copper ore tailings at 500–600 °C. The extraction rate of SiO 2 and Fe 2 O 3 was ca. 82% and below 2%, respectively. Hematite was not converted to soluble NaFeO 2 in low temperature NaOH–NaNO 3 molten system. Mesoporous MCM-41 was synthesized using a hydrothermal method with the extracted Na 2 SiO 3 . The analysis of small angle XRD, N 2 adsorption–desorption and HRTEM showed that the silica sample had a regular hexagonal structure of typical mesoporous MCM-41. The obtained MCM-41 silica had a BET specific surface area of 946.68 m 2 /g and mesopore volume of 0.76 cm 3 /g.

In this work, alkaline silicate wastes including blast furnace slag (BFS), coal fly ash (CFA), straw ash (SA) and lithium slag (LS) were used to remove Cd2+ from aqueous solution. The removal performances of Cd2+ by silicate wastes were compared in batch experiments, and the removal mechanisms by SA were proposed. All of four silicate wastes showed high acid neutralization capacity with solution pH increasing from 2.0 at initial to 6.27–9.70 at equilibrium. The removal of Cd2+ by four wastes followed the pseudo‒second‒order kinetic model and the equilibrium data were well described by the Langmuir isotherm. The maximum removal capacity of Cd2+ for four wastes had the sequence of SA > BFS > CFA > LS. The SA with the maximum removal capacity of 88.75 mg/g was the best adsorbent for Cd2+ removal. The XRD tests showed that Cd2+ could be chemically precipitated as Cd(OH)2 on the SA surface. The FTIR and XPS analysis exhibited that oxygen functional groups of SA could undergo surface complexation with Cd2+. Hydration products such as calcium silicate hydrate derived from SA could immobilize Cd2+ ions through ion exchange. In summary, the removal of Cd2+ by straw ash had a complicate involvement of chemical precipitation, ion exchange and surface complexation with oxygen functional groups.

A novel carbonaceous material (NCM) for Cr(VI) removal from aqueous solution was prepared by pyrolysis using the oily sludge of tank bottom as a raw material. The NCM obtained was characterized by chemical analysis, XRD, SEM-EDS, FTIR and ASAP2010 specific surface porosity tester. The results showed that the NCM exhibited a strong Cr(VI) removal capacity because of the presence of low-valent sulfur compounds in NCM. The maximun removal rate of Cr(VI) was 93.5% when the solution containing 40 mg/L Cr(VI) was treated using 1.0 g/L NCM, prepared under the optimum conditions at a pyrolysis temperature of 750 ℃, a heating rate of 4 ℃/min, a nitrogen gas flow of 150 ml/min and a pyrolysis time of 60 min. NCM was an inorganic material containing 22.70% carbon. Elements C, S, Fe, Al, Ca and Si constituted the porous skeleton structure of NCM. The element C in the material partly existed in group −CH3, −CH2- and C–S. The elements S, Fe, Al, Ca and Si were partly embedded in NCM in the forms of crystalline minerals such as CaAl2Si2O8, CaS, FeS, Fe1-xS and Fe7S8. The pore size distribution was mainly in the range of 35 to 500 nm inside NCM. It has been proven for the first time that an oily sludge of tank bottom can be used to prepare the NCM for Cr(VI) removal by using a pyrolytic technique.

A microbial bio-based collector was isolated from iron mine soil using a combination of flotation and culturing techniques. Four microbial strains with greater than 75% recovery of pure hematite were separated using the technique. Classification and identification of the 4 strains by 16S rDNA sequences were conducted. Among them only 1 strain, termed F3, can act as a collector for hematite, as it is not pathogenic to humans. The morphology and hematite adsorption (by scanning electron microscopy; SEM), composition, zeta potential and hydrophobicity of strain F3 were further evaluated. Based on the changes in the zeta potential and hydrophobicity of a hematite surface before and after adsorption with F3, its adsorption mechanism was also analysed. The results revealed that the combination technique of flotation and bacterial culturing is a highly effective technique for isolating bio-collectors from iron mine soil. Two flotation stages were required to isolate strain F3, which belongs to the genus Stenotrophomonas . This rod-shaped bacterium had CH 2 , CH 3 and phosphate groups on its cell wall that imparted strong hydrophobicity and negative charge. Adsorption of strain F3 reduced the zeta potential of a hematite surface and enhanced its hydrophobicity. The adsorption of F3 to hematite is presumed to be through chemical adsorption. Therefore, strain F3 can be used as a bio-collector for hematite flotation.