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Removal of Dilute Toxic Anions in Wastewater Using Aluminum Hydroxides Co-Precipitation Method

Sep 13, 2010

The future phosphate rock deposits in South Florida contain a significant fraction of dolomite. The high MgO content of the rock is undesirable in the production of phosphoric acid. Several flotation schemes have been attempted to separate dolomite from phosphate rock. Alternately, Selective Flocculation process has been suggested to separate dolomite from apatite. A high MgO content rock was simulated by a 30:10:60 synthetic mixture of apatite, dolomite and silica. Single mineral selectivity was observed in the mixed mineral systems apatite-silica and dolomite-silica with Polyacrylic acid (PM) and Poly(ethylene oxide) (PEO) flocculants respectively but not realized in apatite-dolomite system with PEO flocculant. Heteroflocculation, suspected to be the major reason for loss in selectivity, was minimized by addition of a Site Blocking Agent (lower molecular weight fraction of PEO). Process parameters such as size reduction schemes, flocculant/SBA dosage, and pH were investigated to achieve the desired separation. The selectivity obtained in binary mixed mineral tests was translated into the ternary mixed mineral system, viz. apatite-dolomite-silica. In this presentation surface chemical characterization of the samples and their flocculation behavior will be discussed.

Jan 1, 1994

By Mengxiong Guo, Xuxin Shao

The recent depressant research is summarized, and a new kind of depressant (SCO) has been put forward in this article. Using Na-oleate as a collector and SCO as a depressant, separation of dolomite and phosphate was studied. When SCO was added in the concentration range of 80 g/t to 2kg/t at pH 9.5 ± 0.2, dolomite was absolutely depressed, and apatite kept its floatability. Interestingly, in the mixture of phosphate and dolomite, the dolomite floated. The reasons for such a behavior are investigated through flotation and electrokinetic studies. It was found that the adsorption of dissolved species on dolomite and phosphate resulted in reverse flotation. A concentration of 31.59% P205 and 83.87% recovery of P205 was obtained from the mixture of phosphate and dolomite (2:1) with 26.6% P205 using 210 g/t SCO and Na-oleate 4.93*10-5 M at pH 9.

Jan 1, 1989

By G. Zaitsev

In mining and mineral processing, ammonium and nitrate from residues of explosives and other sources are discharged to the aquatic environment. Nitrogenous compounds in mine water can adversely affect the aquatic environment. The aim of this work was to study the biological removal of nitrate from cold inorganic mine water at the pilot-scale in an operating underground mine. Seven-months pilot testing on biological removal of nitrate from inorganic mine water was successfully performed in denitrifying fixed-bed biofilm reactors. The feed to denitrification bioreactors contained 11 mg NO3--N/L. Methanol was added as an external carbon source to the denitrifying bio-reactor since the inorganic mine water contained only traces of organic compounds (<CODCr (50 mgO2/L). Nitrate removal reached 75 g NO3--N/m3/d with removal efficiencies above 95% at temperature below 4°C. Thus, removal of explosives-residues from cold inorganic mine water was shown in pilot-scale biofilm reactors.

Jan 1, 2014

By J Kokado, N Hatta, S Yabushita

A theoretical model is described for prediction of the capacity of fines from porous ores, such as cokes and sintered ores, to be removed by a pneumatic, horizontal-type classifier prior to charging into a blast furnace. First, the influence of variation in the apparent density and drag coefficient of porous ores on removal efficiency is analysed from a stochastic standpoint. The effect on efficiency of collisions between particles in the classifying region is then examined analytically in relation to the ratio of the mass flow rates of particles and air (the loading ratio). Finally, a theoretical model is constructed that takes these factors into account. Theoretical and experimental results are compared and classifying efficiency is discussed from both experimental and theoretical viewpoints.

Dec 1, 1993

By K. N. Han, M. C. Fuerstenau, T. B. Onlin

An investigation of the removal of finely divided silica, coal, and alumina particles less than 20,µm in size has been carried out using liquid fluidized and packed beds. The bed particles used included 48x100, 100x150, and 150>200-mesh silica, corundum, and ilmenite particles. Important variables examined included surface charge, flow rate, pH and amount of bed particles. Surface charge has been identified as the most important variable in this system. Van der Waals force also assumes a very important role in the recovery of fine particles in fluidized and packed beds. In addition to interaction between large and fine particles, interaction between fine particles themselves assumes an important role in the overall recovery.

Jan 1, 1987

By B. Jin

Removal of fluoride and chloride by alkaline washing from direct lead smelting dust which originated from an Ausmelt furnace is reported. The results show that the fluoride removal efficiency increases with an increase of alkaline concentration, alkaline washing temperature and time. The L/S ratio has little effect on fluoride and chloride removal efficiency. A new flow sheet for removal of fluoride and chloride from the dust was successfully proposed according to the results. Fluoride and chloride removal efficiencies are more than 53.68% and 63.18% respectively using the flow sheet under the optimum parameters of temperature 338 K, L/S ratio 3:1 and alkaline washing time of 1.5 h. The contents of fluoride and chloride in the alkaline washing residues can meet the standard of zinc purity as hydrometallurgical materials for zinc processing.

Jan 1, 2014

By Jerome P. Downey

In the thermal treatment of electric arc furnace (EAF) dusts, zinc is reduced, volatilized, and ultimately recovered either as liquid metal in a splash condenser or as solid zinc oxide in bag filters. During the process, the duet&apos;s chlorine and fluorine content also enters the gas phase and condenses as dross in the splash condenser or as salts which contaminate the zinc oxide product. Pretreatment of EAF dust by pyrohydrolysis appeared to offer a means of minimizing the duet&apos;s halogen content. The primary research objectives were to experimentally verify the technical viability of pyrohydrolysis and delineate the process parameters requisite for efficient halogen removal. To this end, representative EAF duet samples were secured and characterized by x-ray diffraction, scanning electron microscopy, and Mössbauer analyses. Specific- experimentation focused on the response of halogen extraction to variations in temperature, retention time, water vapor partial pressure, and various additives. The experimental results proved that 97 to 99 percent chlorine extraction and 80 to 85 percent fluorine extraction are consistently achieved when EAF dusts are blended with silica and roasted at temperatures of 850°C or greater in a furnace atmosphere of 75% steam (diluted by air). A statistical analysis further established that more than- a single optimal point exists, thus affording flexibility in parameter selection (e.g., by increasing temperature, the necessary retention time and additive concentrations are decreased). The findings substantiate the feasibility of pyrohydrolysis roasting in reducing the chlorine and fluorine in the EAF dust to a level that will obviate industrial concerns about halogen contamination. The end-product of the pyrohydrolysis procedure is a de-halogenated, self-fluxing calcine which can be directly charged to a plasma or flame reactor. The paper includes design parameters and flow diagrams illustrating the pyrohydrolysis process integrated with the plasma and flame reactor technologies.

Jan 1, 1992

By J. R. Tonry

In the grinding of dry non-metallic materials such as rocks, ores, gypsum, lime, and cement clinker, it is recognized that only a relatively small portion of the energy is utilized for actual size reduction, and the major portion of the energy used is converted into heat. As a result, heat is generated inside grinding mills imparting to the ground product a higher temperature than that of the mill feed. In some cases, as for instance in grinding cement clinker and gypsum into finished cement, it may be desirable to keep this temperature increase within certain limits, to avoid any change in the properties of the product and, because consumers may specify a maximum temperature of the finished product for reasons associated, with the tulimate use of the cement. The actual proportions of heat and useful work are somewhat indefinite. Some tests have indicated that nearly all the energy is converted into heat, and. other investigators have found that they could account for "everything except the noise." Investigations sponsored by the American Institute of Mining and Metallurgical Engineers, and carried out with an adiabatic calorimeter, indicated that a surprisingly high 19 percent of the energy might actually be used for size reduc¬tion. However, for the purpose of the following discussion it will be assumed that: (Fig. 1) 10% is lost in motor and gears 10% is lost by radiation and convection from the mill body 10% is used for size reduction, and. that 70% of the energy input leaves the mill as heat in the ground. product. A typical example (Fig. 2) would be a 7x22-ft tube mill operating in open circuit, driven by a 400 hp motor, charged with 77,000 lb of grinding media and producing 70 bbl or 26,300 lb of cement per hour. Reducing this cement from a clinker size of 96 percent passing a No. 16 mesh sieve to a specific surface of 3,230 sq cm per gm (Blaine) will increase the temperature of the cement approximately 143F above the temperature of the feed, as explained later. If the tempera¬ture of the clinker therefore is 125F, the finished cement will be 268F, which in some cases may be too hot. : When cement temperatures approach a range during grinding where dehydration of the gypsum becomes a problem, a logical consideration would be some means of reducing the temperature before it attains the range conducive to gypsum dehydration. Regardless of the varying degrees of heat generated within the mill or mills during grindingto various finenesses, consideration of the maximum safe limit for any type of cement being ground, which may vary fromplant to plant, govern in refining the mill circuit to obtain a safe temperature range. All plants are not necessarily required to do the same cooling job, and may or may not use cement coolers following the grinding circuit. (Not discussed in this paper). In the past, various means have been employed for controlling this temperature increase, Such means have included water cooling of the outside of the mill shell; equipping the shell with cooling fins; injection of moisture inside the mill; ventilation through the mill; and., in cases of closed-circuit grinding, drawing cooling air through the classifier; the purpose in all such cases being to remove heat from the grinding system.

Jan 1, 1958

By X. Baolin, R. Guru, M. Peiravi, M. K. Mohanty, Z. Qian, R. Ma, Z. Yude, L. A. Ackah

"Acid mine drainage (AMD) is produced when exposed pyrite (FeS2) reacts with air and water to form an acidic solution that usually contain contaminant levels of heavy metal ions. AMD can potentially contaminate surface water and soil if not treated. The primary objective of this study was to investigate the removal of dissolved aluminum, iron and zinc metal ions from natural AMD using water treatment residue (WTR), a low-cost adsorbent. WTR sorbent generated as waste material in drinking water treatment plants (WTP) was characterized and utilized for the sorption of Al, Fe and Zn in AMD collected from an abandoned coal mine site in southern Illinois that generates approximately 20 gallons per minute of AMD. Sorption experiments were performed using batch technique to obtain rate and equilibrium data. The effects of various parameters on sorption capacities of WTR were observed by varying contact time, pH of the AMD and WTR dosage. The adsorption studies showed rapid uptake in general for the first 80 minutes for Fe and Zn but much earlier for Zn. Further increase in contact time did not show significant change in equilibrium concentration indicating the onset of adsorption equilibrium. After the batch treatment of the AMD water with the WTR, the removal of Al, Fe and Zn were 99.8%, 99.85% and 95.5% respectively. The pH of AMD increased from 2.64 to a near neutral point of 6.74 after treatment. The laboratory results show that the low-cost WTR, which is an abundantly available industrial waste, has proven potential to significantly reduce the high metal ions in acid mine drainage. INTRODUCTION Mining activities provide the basic raw materials needed for infrastructure development and economic growth world-wide. However, it is well recognized that mining activities have been the cause of a variety of environmental pollutions, including AMD. Water seeping out of an old abandoned mine is generally characterized by low-pH with heavy loads of dissolved sulfates (SO4) and metal species such as Fe, Al and Zn among other dissolved elements categorized as toxic metals. The Bureau of Land Management’s Abandoned Mine Lands (AML) program reported the existence of about 46,000 abandoned mines in the United States. Several environmental problems have been reported to be associated with these mined out sites such as heavy metal poisoning, loss of vegetation, air pollution etc. (Boulanger & Gorman, 2004)."

Jan 1, 2017

By Yang Jian-guang, Deng Zi-xiang, Zhang Xu-liang, Li Jun-yuan

"Hyperaccumulator biomass harvested after heavy-metal phytoremediation must be considered as hazardous waste that should be contained or treated appropriately before disposal or reuse. As a potential method to detoxify the biomass and to convert this material to a suitable bio-energy resource, the hydrothermal upgrading process was applied to remove heavy metals and upgrading crude bio-oil from Pteris vittata stems and leaves harvest. Parameters such as material granularity, temperature, Liquid/Solid (L/S, ml/g), pressure, duration and catalysts were examined for their effect on the removal efficiency of heavy metals and upgrading efficiency of crude bio-oil. Maximum heavy metal removal efficiency of>99% and crude bio-oil upgrading efficiency of 83% were attained with an 200 mesh (75 µm) granularity, LIS 40:1and23 MPa at 380°C in the presence ofO.l mol L-1 K2C03 for 30 min. GC-MS analysis results show that the resulting bio-oil mainly consists of benzene 11 %, ketone 42%, alcohols 14%, alkene 15% and ester 11 %, etc., and the relative molecular weight distribution lies in 94-282, carbon number distribution lies in 6-18, calorific value is 32MJkg-1.IntroductionPhytoremediation of soil or water with hyperaccumulator has been extensively explored in recent years [1-4]. Living plants can clean up soils or waterways. This approach exploits the ability of various plant species to thrive in high metal environments where large amounts of toxic elements are accumulated, such as heavy metals, and is particularly appropriate when slow remediation of relatively low metal concentrations is acceptable. Advantages compared with existing remediation methods include the minimal site destruction and destabilization, low environmental impact, and favourable aesthetics; advantages compared with biosorption include continuous in situ regeneration of the biomass, and the ability of living plant cells to supplement passive sorption of metals with metabolic mechanisms of metal uptake and detoxification [5-8]."

Jan 1, 2014

By C. Villa Diniz

It is proposed that battery grade Mn02 can be produced directly from a manganese ore from Azul Mine in Brazil, by leaching with HCI to remove heavy metals selectively. We are working to find a way of selectively separating Cu, Ni, Co, Pb and Fe from the resulting acidic manganese chloride solution, to detoxify it and produce marketable chloride solution. Chelating ion exchange resins are proving more promising for this separation than solvent extraction with commercially available reagents. Results from batch and column ion exchange tests that characterize the behavior of copper, nickel, cobalt, lead and iron are reported.

Jan 1, 1999

By Liyuan Chai

In this study, spent grain was used as an adsorbent for the removal of Hg(II) from aqueous solutions, the process parameters such as contact time, solution pH, adsorbent dose, and initial Hg(II) concentration were studied in batch experiments. The initial adsorption process was fast, 91.08% of adsorption occurred within 5 min and equilibrium was reached at around 30min. Adsorption process was found to follow pseudo-second-order kinetics. The equilibrium data were better fitted to Langmuir isotherm than Freundlich isotherm with the maximum adsorption capacity 41.36 mg/g. The structure and component of spent grain before and after adsorption of Hg(II) were investigated using scanning electron microscope(SEM) and energy dispersive X-ray analysis(EDAX), these analysis also confirmed the adsorption of Hg(II) onto spent grain. The results indicated that spent grain had potential as a new inexpensive adsorbent for Hg(II) removal from aqueous solutions.

Jan 1, 2009

By Creelman C. A

The removal of a horizontal piIlar between Nos. 9 and 11 levels (1,116 feet from the collar of main shaft) was successfully carried out by blast hole drilling, and, to the best of the authors&apos; knowledge, this mass blast of 40,000 tons of ore (requiring the use of 7,150 Ibs. of explosive and 5,385 feet of primacord) was the first occasion on which a task of this magnitude has been carried out underground in an Australian mine.Blast hole drilling was introduced by this company approximately fifteen months ago at New Cobar Mine in sub-level stoping.This experimental drilling and blasting gave very valuable information as to the correct technique to be adopted when the final plans were being prepared for the removal of the horizontal pillar at New Occidental Mine.The dimensions of this pillar were approximately 15 feet long, and from 40 to 60 feet wide, and 65 feet in depth.The block of ore extended to 35 feet above the level and 30 feet below, the upper section being partially excavated to form the bell-hole floor and grizzly chambers used for drawing off the broken ore in the shrink stope above the No. 10 level.Description of Ore-bodyThe main ore-body is situated almost vertically in a well-defined shear zone at the junction of sandstone and slate, the sandstone forming the eastern and the slate the western wall.The ore-body consists of highly silicified slate (chert) sparsely impregnated with sulphides, containing a small percentage of copper and bismuth.The total length of the ore-body is approximately 450 feet, with a maximum width of 60 feet in the main section, which is about 200 feet long.This is the section shown in longitudinal and cross-section (Fig. 1).The ore-body is divided by a horse of mullock in the northern end into two legs, the eastern and western, which are approximately 250 feet long and averaging 25 feet in width.This ore-body is strong, hard and abrasive with extremely strong walls, an ideal proposition for open stoping and mass blasting.MiningIn all levels above No. 9 the cut and fill method of ore extraction was adopted. On Nos. 10 and 11 levels the shrinkage method was introduced with economical results, and no difficulty had ever been experienced with shabby or bad walls.Shrink stoping had been carried upwards from No. 11 level to within 10 feet of No. 10 level, when mining hazards developed, and instead of...

Jan 1, 1944

By Katsutoshi Inoue

Pectic acid gel crosslinked with epichlorohydrin was found to have very high selectivity to lead(II) and iron(III) ions over zinc(II) ion compared with commercial weakly cation exchange resins containing the same carboxylic functional groups, suitable for removing small amount of impurity metal ions from waste zinc plating solutions. In order to lower the cost, new adsorption gel was prepared from orange juice residue containing pectic acid by crosslinking with epichlorohydrin, which was also found to be suitable for removing these impurities. Further, very cheap adsorption gels was prepared not only from orange but also from apple juice residues by a simple method through just saponificating pectin substances contained in these residues into pectic acid by calcium hydroxide followed by water washing and drying. These adsorption gels exhibited excellent adsorption behaviors for removing the impurity metal ions away from zinc.

Jan 1, 2003

By Gardner H. J, Wadsley m. W

Bauxite from the Weipa and Andoom (North Queensland) deposits was treated to provide a low-iron raw material for high- alumina refractories or aluminium chloride manufacture. The operation involved passing crushed, calcined bauxite continuously through a single laboratory shaft furnace. Consecutive sulfidation and chlorination of the iron minerals within the furnace resulted in a beneficiate containing less than 2% (wt.) Fe203 and by-product ferric chloride con- taining only traces of aluminium.

Jan 1, 1979

By K. C. Sole, M. Makonese

Bushveld Belco is commissioning a plant for production of electrolyte used in vanadium redox flow batteries. Owing to the source material, the electrolyte is contaminated with Fe, at concentrations up to 140 mg/L, which negatively affects battery performance. This study examined the use of ion exchange to reduce the Fe concentration to the target value of < 100 mg/L from a feed solution containing 100 g/L V in 4 M H2SO4. Four resins with possible application were identified: Puromet MTS9570, Puromet MTX7010, Puromet MTS9500, and Puromet MTC1600H. Puromet MTS9570 outperformed the other three resins in all batch experiments with respect to loading capacity and selectivity over V, and was evaluated for Fe removal in fixed-bed column loading tests. Based on these data, preliminary sizing and design of a full-scale column was undertaken. Owing to the difficulty of eluting this resin, a philosophy of discarding the resin on loading to full capacity was considered. These data revealed that, despite the high selectivity of this resin for Fe over V, it would be too expensive and impractical to use this resin for full-scale operation under such conditions. It is recommended to remove iron earlier in the flowsheet prior to generation of the 4 M H2SO4 electrolyte.

Dec 11, 2024

A process was developed, on a laboratory scale, for the removal of iron oxides from Weipa pisolitic bauxite. The technique involves the chemical reduction ofthe iron oxides by carbon, followed by selective removal of the iron species by acid leaching or chlorination.To remove more than 90 per cent of the iron it is necessary to reduce the iron oxides substantially to iron metal by heating the bauxite, pre-calcined at 650-800&#176;C, with reactive carbon at 1040-1100&#176;C. Reduction proceeds via the intermediate formation of hercynite (FeO.Al2O3) and difficulties have been encountered in reducing hercynite formed under less favourable reduction conditions.Following reduction, efficient selective removal of iron species is readily effected by acid leaching using dilute hydrochloric acid at 100&#176;C, or chlorination at 500-750&#176;C using Cl2, Cl2/N2, or Cl2/N2/CO mixtures.After removal of unreacted carbon, the final products contain 0&#183;5-1.0 per cent Fe203 and 87-92 per cent Al203.

Jan 1, 1971

By M. Omneya El-Hussaini, M. Galal Abdel Wahab, A. Mohamed Mahdy, M. Fathi El Shahat

"Um-Gheig Pb-Zn representative sample was collected from the main adite of Um-Gheig mine along Red Sea coast in Egypt. Its chemical analysis shows that, it contains 16% Zn, 2.3% Pb, 0.1% Cd and 0.1% B as elements of interest. After H2SO4 agitation leaching, the chemical composition of Um- Gheig Pb-Zn deposit ore residue assayed 2.26% Pb, 1.5% Zn, 0.085 % B and 0.01% Cd. This residue was leached with 20% HCl at S/L ratio 1/3 for 2 hours at 80o C. The chloride leach liquor was found to contain 18 g/l Pb, 13 g/l Zn, 0.1 g/l Cd and 0.75 g/l B with the corresponding leaching efficiencies 79%, 86%, 100% and 88% respectively. Lead was precipitated from the chloride leach liquor using concentrated H2SO4 to obtain PbSO4 with precipitation efficiency 96%. While boron was extracted by the selective resin Amberlite IRA743 with loading efficiency of 80%. On the other hand, Zn and Cd were precipitated using Na2S solution with 86.7% and 100% recovery efficiencies respectively.IntroductionLead-zinc ores occur in Egypt in a few localities distributed along the Red Sea coast between El Qusier and Ras Banas.. The reserve of the ore deposits has been estimated by Soviet and German Experts to be about 900,000 Ton, [1]. Onal et al., [2] recovered Pb from Pb–Zn sample containing 10.17 % Pb and 10.98 % Zn from Aladag in Turkey. El-Sherif, [3] used concentrated HCl to leach lead-zinc ore sample of Um-Sammuki area in Egypt. As had been published by Marchioretto et al. [4], the precipitation of heavy metals with lime, sulfide and caustic soda are the most commonly used economical methods for metal removal. Lead was completely removed from the anaerobically digested sludge by precipitation with NaOH and Na2S at waste water treatment plants. Mahdy et al., [5] had successfully extracted boron from the bittern solution of Qaron Lake by ion exchange resin (Amberlite IRA 743). The extraction of boron was mainly depending upon the pH value. They extracted 80% of boron at pH 5.5, while at pH 3.9 about 74% boron was extracted. Kabay et al. [6] used the column-mode to remove 1g/l of boron from geothermal waste water of the Kizildere-Geothermal Power Station by using Diaion CRB 02 Nglucamine- type chelating resins. In this regard, the removal of lead, cadmium and boron allow the residue to be reclassified as non hazardous material."

Jan 1, 2008

By Edward Rosenberg

The synthesis and characterization of silica polyamine composites modified with a variety of sulfur containing ligands is described. The two most successful ligands in terms of sulfur in-corporation and mercury capture are ethylene sulfide and carbon disulfide. The ethylene sulfide forms either an amino mercaptane or a polysulfide upon reaction with amino groups on the composite. The carbon disulfide undoubtedly forms a dithiocarbamate functional group upon reaction of the amino group under basic conditions. Both materials posses excellent capture kinetics and capacities for mercury, Once captured, the mercury is extremely difficult to remove from the composite materials, even with concentrated acids, and they easily pass the TCLP test. The materials are compared with related thioether modified silica polyamine composites and appropriate potential applications are discussed.

Jan 1, 2003