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By Supachai Surapunl

The distribution behavior of VA minor elements (As, Sb and Bi) in the smelting stage of the Mitsubishi process were evaluated thermodynamically based on thermodynamic data and operating data. The fractional distributions between the gas, slag and matte phases considered as the degree of vapor saturation of l.0 are as follows: 53.8, 27.2 and 19% for As, 23.6, 56.6 and 19.8% for Sb, and 91.3, l.1 and 7.6% for Bi, respectively. Arsenic is mostly distributed to the gas and slag phases. It is effectively eliminated by volatilizing and slagging. Antimony is mainly in the slag phase, which is suitably removed by slagging. Bismuth is easily vaporized to gas phase. The degree of vapor saturation has a large effect on the distribution behaviors of the three elements between the three phases. The amount of a minor element in the charge has an effect on the distribution of As but no effect on the distributions of Sb and Bi. Increasing matte grade and temperature results in the change of distributions for As and Sb, significantly. The change in the distribution ratio between slag and matte phases also considerably affects the distributions of As and Sb. The distribution behavior of Bi is not significantly changed by the change in matte grade, temperature and distribution ratio.

Jan 1, 2003

By C. R. Palmer

The Bureau of Mines investigated the use of ion-exchange technology for the recovery of precious metals from cyanide leach and spent electrolytic solutions. This research included adsorption of gold and silver on both weak-and strong-base anion-exchange resins. The effects of nickel, mercury. and iron on precious metal loading of strong-base resins were also determined. Due to the nonselectlvity of strong-base resins, selective elution also was investigated. Both commercially available and experimental weak-base anion-exchange resins were tested. None of the commercial weak-base resins tested were suitable for a caustic-cyanide system owing to their low recovery of precious metals at pH 10 or above; however, three experimental resins have possible application. Continuous tests conducted with mill cyanide solution in a multicompartmented ion-exchange column using strong-base anion-exchange resins adsorbed nearly 100 pct of the precious metals as well as the iron and nickel. During the elution of this loaded resin the iron was first removed with NaCI plus NaOH; then nickel with dilute H2S04 or HCl; finally gold and silver with thiourea in dilute HCl.

Jan 1, 1988

By Seshadri Seetharuman

The present paper summarises a series of measurements of the interaction parameter of oxygen in liquid copper with respect to a third element, e(M)o, where M is Mn, Zn, As, Se or Te which are common impurities in the liquid metal. The technique employed was the solid electrolyte galvanic cell method. The cell used may be represented as Pt, W or cermet / Cu-O-M // ZrO2 - CaO // AO, A /PT where AO/A represents a suitable oxide/metal reference. The measurements indicate that Mn and Zn interact very strongly with oxygen in liquid copper while, in the case of arsenic the interaction parameter is nearly zero. The behaviour of the elements Se and Te is unique with respect to oxygen interactions in copper bath. At oxygen levels, xo= 10-4 ? 10-5, the apparent interaction parameters are negative, comparable to that for sulphur. On the other hand, at lower oxygen levels, the results indicate that the interaction parameter values are positive. The results are discussed in the light of some of the theoretical models for solute interactions in liquid metals.

Jan 1, 1993

By Junji Shibata

The waste acid mixture whose main component is phosphoric acid, is discharged from the etching process in the liquid crystal production industry. In order to separate impurity acids from the phosphoric acid, trioctyl phosphate (TOP) is used as an extractant. TOP can extract acetic and nitric acids selectivity. The extraction and stripping operations are carried out for the acid mixture by beaker-scale experiments and countercurrent multistage operations with mixer-settler equipment. TOP selectively extracts the acetic and nitric acids in the acid mixture. From the results of the McCabe-Thiele analysis obtained by beaker-scale tests, the extraction for acetic and nitric acids are approximately 100%, respectively, by 6-stage extraction with a phase ratio (A/O) of 0.4. On the other hand, almost all of acetic and nitric acids are stripped with water from the organic phase by 4-stage stripping with a phase ratio (A/O) of 1.0. About 95% of acetic and 98% of nitric acids can be removed from the acid mixture without extracting phosphoric acid in case of the mixer-settler equipment operation. There are several steps such as slicing, lapping, chemical etching and mechanical polishing in the silicon wafer production process. The chemical etching step is necessary to remove any damaged layer caused in the slicing and lapping steps. The typical etching liquor is the acid mixture comprising nitric acid, acetic acid and hydrofluoric acid. The waste acid is treated by a neutralization method with a high alkali cost and balky solid residue. A solvent extraction method is applicable to separate and recover each acid. Acetic acid is first separated from the waste liquor using 2-ethlyhexyl alcohols as an extractant. Then, nitric acid is recovered using TBP (Tri-butyl phosphate). Finally hydrofluoric acid is separated with TBP solvent extraction. The expected recovered acids in this process are 2mol/L acetic acid, 6mol/L nitric acid and 6mol/L hydrofluoric acid. The yields of this process are almost 100% for acetic acid and nitric acid. On the other hand, it is important to recover and reuse the metal values contained in various industrial wastes from a viewpoint of environmental preservation. Most industrial products are made through processes to separate impurities in raw materials, solid and liquid wastes being necessarily discharged as industrial wastes. Chemical methods such as solvent extraction, ion exchange and membrane separation, and physical methods such as heavy media separation, magnetic separation and electrostatic separation are considered as the methods for separation and recovery of the metal values from the wastes. Some examples of the application of solvent extraction to the treatment of wastes such as Ni-Co alloy scrap, Sm-Co alloy scrap, fly ash and flue dust, and liquid wastes such as plating solution, the rinse solution, etching solution and pickling solution are introduced.

Jan 1, 2003

By Katsutoshi Inoue, Shafiq Alam

Several novel types of chemically modified chitosan were prepared by immobilizing functional groups of EDTA and DTPA onto polymer matrices of chitosan in order to investigate their potential for mutual adsorptive separation among rare earths. Following the batch wise adsorption tests to elucidate their basic adsorption characteristics for rare earths, mutual separation was carried out using a column packed with the chemically modified chitosan. The separation between Sm(III) and Y(III) was tested using a column packed with EDTA-type chitosan while mutual separation among 4 light rare earths, La(III), Ce(III), Pr(III) and Nd(III) was tested using a column packed with DTPA-type chitosan. In both cases, satisfactory mutual separation was achieved by the chromatographic operation using these chemically modified chitosan.

Jan 1, 2014

By W. G. Davenport

Chapter 4 examined Inco (oxygen) flash smelting of pure chalcopyrite concentrate. It showed that the oxygen and flux requirements for auto thermal smelting are readily determined by a matrix calculation. This chapter extends this matrix approach by applying it to a multi-mineral concentrate.

Jan 1, 2001

By A. M. Blount

In 1983, a final ruling of the U.S. Occupational Health and Safety Administration (OSHA) specified that chemicals containing >0.1 % of a carcinogenic substance or > 1 % of a substance hazardous to health must be labelled. Amphiboles of the fibrous or asbestos-type must be quantified at levels of 0. I % whereas the status of non-fibrous types is not finally determined at this time. Tremolite and actinolite can possibly be measured to 0.1 % by XRD, but anthophyllite cannot be so measured. Recently the International Agency for Cancer Research (IARC) has designated quartz as a suspected carcinogen, and its quantity must be measured to the 0.1 % level. Thus, it has become Increasingly important to be able to detect and quantify minerals in bulk samples down to low or "trace" levels. It has been found that minerals needing to be quantified can often be concentrated by microcentrifuge and counted by means of polarized-light microscopy. For example, amphiboles in talc samples can be separated by using a heavy liquid (thallium formate-malonate) of density 2.810. Talc floats, and amphiboles sink. After centrifuging, the denser particles are removed from the bottom with a Pasteur pipette and placed in a clean centrifuge tube. Distilled water is added to the tube containing the denser minerals and the tube centrifuged again. After several washings with distilled water, the sample is removed along with a drop of water to a clean glass slide. A drop of 1 .584 refractive index liquid and a cover glass are placed over the dried sample. The slide is scanned for particles greater than 5 um in length and having an aspect ratio greater than 1:3. These are checked for refractive index, sign of elongation and extinction angle to differentiate them from talc particles on edge and other minerals. Amphiboles have all indices greater than 1.584, and talc has all indices equal to or lower than this value. Alternately the heavies at the bottom of the centrifuge tube can be filtered through a nucleopore filter. After the filter has been washed with distilled water and dried, a 1.584 refractive index liquid renders the filter transparent in two of the four extinction positions so that a count of amphibole particles can be made directly on the filter. The refractive index-density method which is so useful for talc powders should be equally useful for other nonsoluble industrial minerals.

Jan 1, 1989

By Michael J. Mankosa

The increased emphasis placed on recycling of consumer and industrial waste products has generated a need for advanced separation techniques for recovery of valuable by-products. As a result, the metals recycling industry has made great strides in the recovery of used wire products through the application of chopping and screening processes. Unfortunately, in many instances, the final plastic reject still contains a substantial portion of valuable metal. Typically, this material has been discarded, since an appropriate separation technique has not been available. Recent work conducted by Carpco, Inc. in Jacksonville, Florida indicates that a high-grade metal and/or plastic product can be recovered from this waste material using a novel density separation process. Extensive test work has been conducted using this procedure to validate separation performance as well as equipment capacity. This paper will present the basic operating principle of the separator, as well as results from tests conducted using various feed materials.

Jan 1, 1995

By Marcelo Jimenez Bustos

The Chagres Smelter was the first in Chile to follow environmental regulations to control sulfur dioxide emissions. Because of this, the operation and development plans have had to incorporate environmental planning as part of its policies for almost three decades. The present article shows the development of the environmental standards applied to its operations, investments and operational improvements carried out to meet the regulations and improve competitiveness. Results to-date and future plans are outlined, as well as their impact on operations and the environment.

Jan 1, 1993

By Hal dun Kurama

In thus-study, Bigadic upper zone zeolitic tuff, which contains about 87% clinoptilolite was used as an ion exchanger for removal of Pb++, Cu++, Cd++ and Hg++ ions from wastewater. Bench scale experiments with two different glass columns, were carried out continuously under the closed/ open circuit conditions. Before ion exchange tests, zeolite samples were treated with NaCI (6ml/ min. and 42BV). The effects of particle size, bed volume, pH and flow rate on the ion exchange capacity were determined. Under the best operation conditions, the effect of initial influent solution concentration on ion exchange selectivity was tested. As a-result, it was found that the Bigadiç clinoptilolite had the following ion exchange capacities;

Jan 1, 1995

By C. G. Anderson, L. G. Twidwell

"Throughout the world, there are many orebodies or materials which have significant value but also contain arsenic, antimony, and mercury. As regulations on the transport, exposure, disposition and emission of these elements have become more stringent; it has become increasingly more difficult to derive the values from the resources. This paper outlines the fundamentals of alkaline sulfide hydrometallurgy and its successful application to arsenic, antimony and mercury bearing ores, concentrates, by-products, and other materials.Fundamental Alkaline Sulfide HydrometallurgyHydrometallurgical methods can be employed for treatment of gold, arsenic, antimony, tin and mercury containing materials, concentrates and ores as well as complex ones containing any number of metals. The alkaline sulfide system is one of these and is essentially a mixture of sodium sulfide and sodium hydroxide. This is a unique hydrometallurgical system as it is a very selective lixiviant for the distinct leaching of tin, gold, antimony, arsenic and mercury [1-7]. Worldwide, it is employed industrially in the CIS, China and the United States for the production of antimony [8-15].As an example, when the system is applied to an arsenic containing material like orpiment, As2S3, a solution of sodium thioarsenite is formed. This is illustrated as:"

Jan 1, 2008

By C. L. Lin

Multiphase, irregularly-shaped randomly-oriented PARGEN particles were grown to determine the breakage/liberation characteristics of such locked particles. The simulated locked particles were randomly broken to establish the liberation characteristics of the broken fragments. The progeny size distributions are consistent with Gilvarry's volume and surface flaw model for single particle breakage. The extent of liberation of both continuous and dispersed phases can be described from the conservation of interfacial area. In this regard the data can be normalized and liberation described for a wide range of dispersed phase grades and dispersion densities.

Jan 1, 1988

By Zuoren Huang

The flowsheet of the hyd.rametallurgical zinc plant which is in use at Zhuzhou Smelters is described. The principal features of the process are fluid bed roasting, continuous calcine leaching, solution purification, zinc electrolysis, electrolyte cooling, and finally, the melting and casting of zinc forms. The Zhuzhou process for the flotation of silver from the leach residue collected on the Moor filters is described. The technical details of the process are outlined and the operating data are analyzed. The flotation facilities are described in detail and concentrate grades and recoveries are presented. The waelz process is used to concentrate In, Ge and Ga remaining in the leach residue after silver flotation. These elements subsequently are recovered by selective leaching in sulphuric acid, and details of this operation also are presented.

Jan 1, 1990

By T. J. White

Xtaltite is the trade name for a generic technology which exploits the well known insolubility of some minerals, which naturally incorporate toxic waste elements, to consolidate and immobilise a range of inorganic waste products. It is a specific case of synthetic mineral immobilisation technology (SMITE) which is already used to immobilise high level nuclear wastes (HLW. Although HLW is highly toxic, it exists in relatively small volumes, occurs in central facilities and may be stabilised at low waste loading (< 10 wt%). In contrast, heavy metal wastes are of considerable volume, therefore Xtalitite waste forms must routinely accommodate high waste loadings (usually in excess of 30 wt% for a particular toxic oxide or combination of oxides) and be suitable for fabrication in remote locations using relatively simple technology. This paper details the methodology underlying Xtaltite, with particular emphasis given to the interplay between solid state chemistry, durability and economic considerations. Specific reference is made to the treatment of arsenious and mercurial wastes.

Jan 1, 1994

By Donna M. Noel

Bacterial strains have been cultivated from solids previously exposed to cyanide that will tolerate 300 ppm sodium cyanide under anaerobic conditions. In selected solid samples, these bacteria have been shown to reduce the level of cyanide from approximately 300 ppm to essentially zero in about 50 days under anaerobic conditions. Various media were investigated, and the nutrients providing maximal growth were ?established .. Degradation of cyanide in sterilized solids was determined for comparison with degradation obtained in bioactive solids. All experiments were conducted at ambient temperature and initial pH of approximately 10.5.

Jan 1, 1991

By Lijun Liu, Yingwei Li, Jianhua Liu, Jinhui Peng

"As essential equipment in the metallurgical industry, current air heat exchangers cannot meet the requirements of high temperature heat transfer. In this paper, an energy efficient air heat exchanger, based on accumulation of the heat generated by microwave absorbing materials, is presented according to heat transfer theory and principles of the microwave field. A tubular shaped heat exchanger was designed and built up through temperature-rising curve, and experimental research of microwave high-temperature air heat exchangers was carried out. It was found from experiments that the tubular shaped heat exchanger fabricated using material B could be used for high temperature heat transfer system, and equilibrium temperatures could reach up to 457—485?.IntroductionHeating or cooling of air by heat exchangers is commonly practiced in a wide range of industries including construction, chemical, machinery, textile, printing, and dyeing [1-3]. Generally such heating or cooling of air is achieved in pipe heat exchangers. There are several drawbacks for such heat exchangers, namely, (i) the limitation of temperature to which the pipes can be heated, (ii) tendency to oxidize at high temperature, and (iii) poor strength of metallic pipes at high temperature. These limitations do not allow pipe heat exchangers to be operated at high temperatures [4-6].Microwave heating of inert solids, which are stable at high temperature, is a possible solution to achieve high temperature of the medium in air heat exchangers. It is well-known that microwave heating is an efficient, clean, safe, easy-to-control heating method. Microwave heating utilizes the dielectric and magnetic properties of a material. When microwaves penetrate and spread into the dielectric material, electrons, ions, etc move in the internal electromagnetic field, while the elasticity of inertia and friction impede these movements. This results in a significant thermal effect, increasing the surface temperature rapidly [7-8]. This paper studies mainly design and experimental research of microwave high-temperature air heat exchanger."

Jan 1, 2011

By Judy Che, Steven Ceccio, Gretar Tryggvason

"A detailed understanding of drop deformation and solidification is essential for quantitative predictions of geometry and properties of parts made by ballistic particle manufacturing processes. Axisymmetric results of towers built by the deposition of multiple drops are presented. In these computations, fluid flow, heat transfer, and phase change are fully coupled throughout the drop deformation and solidification process. The solution method is based on a single set of conservation equations written for all phases simultaneously. The phase boundaries are treated as imbedded interfaces by adding the appropriate source terms to the conservation equations. A parameter study demonstrates the effect of Weber number, Peclet number, and drop deposition frequency on the final shape of the structure. Numerical results show that most successful method of building uniform towers is when two conditions are met. First, each drop solidifies at the same time in the deformation cycle. Second, the cooling rate is slow enough to allow for good adhesion between drops. The ability to predict the final shape of deposited drops will greatly reduce the amount of experimentation necessary to select the desired set parameters for any artifact.IntroductionMaterial deposition techniques based on layering small molten metal drops holds the promise to build small, coherent three-dimensional structures. In this process, numerous 20-100 µm diameter drops are deposited onto a substrate with a low impact velocity (on the order of 5 mis). Both the momentum and trajectory of each drop are controlled precisely to build up complex parts. This material layering technique differs from processes such as spray forming and splat quenching which involve high impact velocities (on the order of 100 mis) and high frequency deposition with little control over individual drop placement. This process of layering small drops can produce parts with near net shape accuracy, while spray forming produces slabs of material which must then be worked to make a usable part. The ability to computationally predict final drop shape and cooling rate has the advantage of allowing the user to select parameters to produce parts with desired shape and mechanical properties. However, the development of such predictive methods requires a thorough understanding of both drop deformation and solidification"

Jan 1, 1999

By Sharon L. Eyer

"FTIR spectroscopy is employed to define mineable ore deposits based on exploration samples. The RAMBO (Robotic Assessment of Mineable Bauxite Ore) technology is operating successfully at an alumina refinery in K winana, Australia, for assessment of a number of critical ore attributes including available alumina, extractable organic carbon and total iron. Classical methods of analyses for these properties require laboratory-scale digestion of alumina ore (bauxite) or XRF analyses.Multivariate calibration is used in the RAMBO system to generate robust mathematical models that are able to estimate classical data from FTIR spectral data. Furthermore the models can highlight regions of ore that are relatively unusual. Unusual ore may be investigated for potential impacts on refinery processes well in advance of mining.The components of the technology are described and some results for an example application (bauxite) are presented. Challenges and difficulties are discussed. The potential to apply the technique to process control is introduced."

Jan 1, 1999

By Saskia Duyvesteyn

Small ion-exchange resin particles provide faster mass transport than conventional-sized beads. Unfortunately, high pressures are needed to pump solutions through columns containing small resin particles. It is preferable to disperse fine resins in the solution being treated. Screens have been used to separate the resin from the solution, but screens do not retain fines created by attrition of the resin particles. We have developed a separation process based on flotation, which relies on the surface characteristics of the resin, instead of size. The resin is conditioned with a surfactant before dispersing it in the solution to be treated; this increases the hydrophobicity of the resin sufficiently for froth flotation, without introducing surfactant directly into the solution. The surfactant adsorbed on the resin surface does not appear to impair the kinetics of metal ion removal. A flowsheet for an effluent treatment process is proposed; other applications are clearly possible.

Jan 1, 1998

By E. A. Trillo, L. E. Murr, R. D. Flores, J. C. McClure, B. M. Nowak

Complex vortex and swirl-like solid-state flow phenomena have been observed in the residual microstructures characterizing the friction-stir welding (FSW) of copper to 6061 aluminum; 2024 aluminum to 6061aluminum,2024 aluminum to 1100 aluminum, 2024 aluminum to 7039 aluminum and 2024 aluminum to 2195 aluminum. These flow phenomena are characterized by intercalation lamellae composed of dynamically recrystallized grain structures of the dissimilar metals which provide a super-plastic-like mechanism for the FSW flow in the solid state; there is no melting and temperatures at the weld center do not exceed about 0.8 TM (where TM is the absolute melting temperature (K)). In experiments to be described and illustrated, optical or light metallography (LM), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) techniques are utilized in examining residual FSW microstructures corresponding to tool rotation (stirring) speeds ranging from 400 to 1200 rpm, and traverse (or actual welding) speeds of 1 to 2 mrn/s.

Jan 1, 1999