Dust Treatment Research Articles

Influence of cement clinker dust on carbohydrates in needles of Scots pine shortly after the application

Clinker dust could be used as an amendment of forest soils to improve the nutrition of trees. Soil pH, needle carbohydrates (glucose, fructose, sucrose, starch), and chlorophyll fluorescence (Genty parameter) were measured about two months after the application of 0.5 kg clinker dust m -2 and in a reference treatment with a slow release N, P, K, Mg fertilizer in a Scots pine plantation. The spatial variation of the soil pH values between the sampling locations and soil layers was not increased by the clinker dust treatment although small-scale heterogeneity in the distribution pattern of dust was observed. The photosynthetic parameters were measured by chlorophyll fluorescence and were not affected by treatments. Dust and fertilizer reduced significantly the concentration of hexoses (glucose + fructose) in 1-year-old needles.

Temporary defluidization in fine powder fluidized beds caused by changing the fluidizing gas

The phenomenon of temporary defluidization of stationary fluidized beds is investigated in this work. Throughout the development of a novel concept for the treatment of converter dust in laboratory experiments, the fluidizing gas was changed during the operational start up from inert gas ( N 2 ) to reactive converter gas (CO, CO 2 and N 2 ). At the same time, a decrease of the bed pressure drop and collapsing of the fluidized bed could be observed. The effect was temporary and after some time the initial fluidization conditions were fully restored. In this study, a systematic investigation is focused on the identification of possible mechanisms for the transitory defluidization and an evaluation of the influence of system parameters on the extent of the defluidization. The experimental work was carried out using two distinctly different systems. The converter dust application is run at elevated temperature of 400–600 °C and allows for the analysis of reactions and sintering effects. As the investigation of effects possibly caused by gas adsorption and changing gas property at the influences the high temperature system was too complex, investigations on these issues were done at ambient temperatures using a much simpler system. Results at ambient temperature show a strong dependence on adsorption effects and the difference in density of the fluidizing gases. The difference in density of both fluidizing gases causes the disturbance in fluidization due to different diffusion rates from the dense phase to the bubble phase. Additionally, at high temperatures, volume reduction due to chemical reaction and sintering effects have been identified as reason causing temporary defluidization. The decrease of voidage in the dense phase results in the collapse of the fluidized bed. Results obtained from our experiments confirm earlier investigations and validate the basis for further investigations in the area. Furthermore, specific parameters were developed for description of the intensity and the duration of the transient phenomenon.

The possibility of recycling flue dust of the ferrochromium productions in Kazakhstan

PurposeThis paper aims to describe a solution for cyclonic flue dust recycling based on the example of ferrochromium producers in Kazakhstan. It includes environmental improvement, which can be assessed in detail based on LCA after the development of a feasibility study of such a proposal.Design/methodology/approachThree pyrometallurgical recycling approaches should be achieved. The first approach is reduction smelting of fine waste in a direct current arc furnace without preliminary agglomeration. The second is reduction smelting of agglomerated waste in a submerged arc furnace, and the third is processing of agglomerated waste with liquid cast iron. The last approach facilitates the reactions of metal oxide reduction by carbon and silicon from the iron with a corresponding decrease in energy and auxiliary material consumption.FindingsValuable material can be produced from ferrochromium dust waste using environmentally friendly technology, including electric furnaces that can operate in SAF regimes and a simple plasma high‐power DC reactor operating under a neutral or reducing atmosphere. Finally, the investigation of waste recycling has developed a novel approach that facilitates metal oxide reduction and provides low energy and auxiliary materials consumption.Practical implicationsResearch into the treatment of flue dust generated in the ferrochromium industry is needed to solve environmental problems not only in Kazakhstan but also in all ferrochromium plants in the world.Originality/valueThe three proposed pyrometallurgical recycling approaches should be achieved on a large scale.

Hydrometallurgical Treatment of Pb Dust for Preparation of Basic Lead Carbonate

ABSTRACT Recycling of lead dust generated at waste lead battery smelter has been attempted to minimize the environmental pollution. For this aim, preparation of lead carbonate from lead dust has been tested with hydrometallurgical processes. The major component of lead dust used in the work was found to be PbS and the fraction less than 325mesh size was about 64%. As a result of leaching with nitric acid, leaching efficiency of lead was more than 95% at the condition of 4N nitric acid, 40°C, and slurry density of 50gr/l. In the leaching of lead dust with sulfuric acid, the addition of nitric acid was essentially required because only 4% of lead dust was dissolved by sulfuric acid without nitric acid. In the carbonation test, carbonation of lead sulfate could be successfully accomplished at the reaction temperature of 30°C while direct carbonation of lead dust was found to give the negligible conversion.

Mathematical Model of Over-micron and Nano-scale Powders Accumulation in a Coke Fixed-Bed Filter

The advances in Electric Arc Furnace (EAF) dust treatment have been slowed down by high treatment costs and the large amount of residue to be processed and disposed. A process of direct separation and recovery of iron and zinc is now under development, which adds environmental and economical perspectives to the EAF dust treatment process. In this process, a coke bed filter can be directly connected to an EAF, collecting metallic iron and slag components, whereas the gas containing zinc and lead vapors flows to a zinc condenser. It results in zero amount of dust liberated to the environment. A two dimensional, axisymmetric and steady state mathematical model describing a coke fixed-bed filter is developed. The model solves coupled equations for gas-powder flow and is specifically applied in the investigation of over-micron and nano-scale powders (similar to EAF dust particle size) collection behavior. The theoretical model results are compared with the cold model experimental results, in which both injection of glass (over-micron) and silica (nano-scale) powders are considered. Microscopic observations and analysis are performed in order to describe better the injected powder behavior through the filter. EAF dust samples morphology is characterized as agglomerates of small particles. Its particle size distribution is obtained by the combination of leaching treatment and image analysis. Calculated results show that the powders particle size distribution has a direct effect in the static hold up. The model has been validated by its enough agreement for static hold up and pressure drop with experimental data from cold model experiments.

Control of silver scurf on potato by dusting or spraying seed tubers with fungicides before planting

Silver scurf of potato caused byHelminthosporium solanl Dur. & Mont. is a blemish disease that has become economically important in recent years and is considered primarily seedborne. The objective of the present study was to compare the effectiveness of various fungicides, alone or in combination, applied to seed tubers prior to planting, in controlling silver scurf on the daughter tubers. Disease incidence and severity were significantly reduced by all treatments in three experimental locations, with the exception of fluazinam, which was not effective. Among the fungicides tested in these experiments, the most effective were fludioxonil and prochloraz-Zn applied as a LV spray (control efficiency of 88% and 82%, respectively) and propineb and mancidan applied as a dust treatment (control efficiency of 78% and 77%, respectively). Azoxystrobin and imazalil treatments were less effective with control efficiencies of 68% and 43%, respectively. None of the various treatments affected crop yields in the three experimental sites.

04/02190 Method for treatment of shredder dust: Kobayashi, A. et al. Jpn. Kokai Tokkyo Koho JP 2003 201,480 (Cl C10B53/00), 18 Jul 2003,Appl. 2002/79. (In Japanese)

04/02190 Method for treatment of shredder dust: Kobayashi, A. et al. Jpn. Kokai Tokkyo Koho JP 2003 201,480 (Cl C10B53/00), 18 Jul 2003,Appl. 2002/79. (In Japanese)

Effect of simulated ambient particulate matter exposure on performance, rectal temperature, and leukocytosis of young Spanish goats with or without tilmicosin phosphate.

Dust is an environmental stressor and can become extensive in agricultural production systems. Thirty-six female, Spanish goats (average BW 21.1 kg, SEM = 1.31; age = 4 mo) were randomly assigned to simulated dust events or no dust, with or without tilmicosin phosphate treatment in a 2 x 2 factorial arrangement of treatments to determine effects on performance, rectal temperature, and leukocyte changes. All goats were fed a standard growing diet (13.6% CP) consisting of 37% roughage and 63% concentrate (DM basis). Feed intake was measured daily, and BW (unshrunk) measured individually every 7 d. The tilmicosin-treated group received tilmicosin phosphate (10 mg/kg BW s.c.) before starting the study. Goats exposed to dust were enclosed as a group inside a canvass tent for 4 h each day and ground feed yard manure dust (mean particle size 100 microm) was aerosolized inside the tent to simulate a dust event. There was one single dust event (Phase I) followed by rectal temperature measurement, and heparinized blood collection for complete cell counts at 0 (pretrial), 4, 12, 20, 44, 68, and 210 h after dust exposure. This was followed by 21 d of chronic dust events (Phase II). The sampling procedures for Phase II were exactly the same as in Phase I, except that samples were obtained daily at 0 (before dust application), 4, 8, and 12 h after each dust event. Dust treatment had no effect (P > 0.05) on feed intake or ADG, but the gain:feed (G:F) ratio was lower (P < 0.05) in the control goats than the dust exposed group. Tilmicosin phosphate-treated goats had a higher (P < 0.05) G:F ratio than untreated goats. Dust exposure increased (P < 0.002), but tilmicosin treatment decreased (P < 0.05) rectal temperature at 4 and 8 h. Dust exposure increased (P < 0.02) blood lymphocyte counts compared with controls. These results suggest that simulated dust events altered rectal temperature and leukocyte counts of goats.

Effect of Chlorine on the Vaporization Behavior of Zinc and Lead during High Temperature Treatment of Dust and Fly Ash

Smelting process is a practical method to treat incineration ash of solid wastes in terms of volume reduction and decomposition/immobilization of toxic materials. In this process, chlorine is a key element to determine the removal ratio of heavy metals such as zinc and lead. The present paper is aiming to give a general review of researches on the effect of chlorine on the vaporization behavior of zinc and lead in molten slag. First, the basic information such as solubility/activity of chlorine in the slag, vaporization mechanism and kinetics relating to chlorides during heat treatment of fly ash are summarized. Then, the vaporization behaviors of zinc, lead and their chlorides during heating are discussed together with important process factors such as atmosphere, temperature, chemical composition and slag matrix. Further, some information on the oxychlorides of Zn and Pb are introduced.

Cement Dust as Filler in NBR Vulcanizates

The use of cement dust waste as filler in rubber vulcanizates is of great interest as a means to get rid of this waste. The effect of cement dust on the properties of acrylonitrile rubber (NBR) was studied and compared with that of carbon black and kaolin. It was found that the surface treatment of cement dust with fatty acid improves its dispersability. The effect of treated cement dust in combination with carbon black on physico-mechanical, thermal aging, swelling resistance and fatigue resistance of the filled vulcanizates was studied.

Effects of aerosolized dust in goats on lung clearance of Pasteurella and Mannheimia species.

The objective was to determine whether the inhalation of large quantities of feedyard dust predisposed the animals to pulmonary bacterial proliferation. Two control groups, C1 and C2, did not receive dust treatments, and two principal groups (P1 and P2) received a total of 14 dust treatments each. The C1 and P1 groups of goats each received a transthoracic challenge of live Mannheimia haemolytica (4 x 10(6) colony forming units, CFU) The C2 and P2 groups of goats each received a transthoracic challenge of live Pasteurella multocida (1.0 x 10(6) CFU/goat). The results showed that dusted animals had fever when compared with non-dusted controls. In addition, dusted animals demonstrated a leukocytosis with neutrophilia after the first dust treatment that was not sustainable. Finally, dusted animals demonstrated pulmonary clearance of two potential bacterial pathogens that was not significantly different from that shown by control (not dusted) animals.

Stabilization of Electrical Arc Furnace Dust with Low-Grade MgO Prior to Landfill

In Spain, the stabilization of electric arc furnace (EAF) dust prior to landfill is mainly carried out using a mixture of lime and Portland cement. This paper describes the treatment of EAF dust with low-grade MgO (LG MgO) and the results are compared to those obtained with a lime and Portland cement mixture used as a stabilizer agent. The effectiveness of the treatment was assessed with leaching tests results. The use of LG MgO allows us to manage this waste as a nontoxic residue according to tests decreed by Spanish regulations. Low-grade MgO acts as a buffering agent giving the final pH mixture a value within the range of minimum heavy metal solubility.

Interactions between tropospheric chemistry and aerosols in a unified general circulation model

A unified tropospheric chemistry‐aerosol model has been developed within the Goddard Institute for Space Studies general circulation model (GCM). The model includes a detailed simulation of tropospheric ozone‐NOx‐hydrocarbon chemistry as well as aerosols and aerosol precursors. Predicted aerosol species include sulfate, nitrate, ammonium, black carbon, primary organic carbon, and secondary organic carbon. The partitioning of ammonia and nitrate between gas and aerosol phases is determined by on‐line thermodynamic equilibrium, and the formation of secondary organic aerosols is based on equilibrium partitioning and experimentally determined parameters. Two‐way coupling between aerosols and chemistry provides consistent chemical fields for aerosol dynamics and aerosol mass for heterogeneous processes and calculations of gas‐phase photolysis rates. Although the current version of the unified model does not include a prognostic treatment of mineral dust, we include its effects on photolysis and heterogeneous processes by using three‐dimensional off‐line fields. We also simulate sulfate and nitrate aerosols that are associated with mineral dust based on currently available chemical understanding. Considering both mineral dust uptake of HNO3 and wet scavenging of HNO3 on ice leads to closer agreement between predicted gas‐phase HNO3 concentrations and measurements than in previous global chemical transport model simulations, especially in the middle to upper troposphere. As a result of the coupling between chemistry and aerosols, global burdens of both gas‐phase and aerosol species are predicted to respond nonlinearly to changing emissions of NOx, NH3, and sulfur.

銅製錬における不純物除去技術

Recently, several removal technologies of minor elements in copper smelting have been developed along with the degradation and the diversification of copper concentrates and also for assuring the quality of cathode. This article reviews the current and new elimination technologies of minor elements for copper smelting based on the recently published papers focusing specifically on arsenic, antimony, bismuth, lead and nickel among various impurities. In this article, the removal technologies in copper smelting are classified into five categories; (1) pre-treatment, (2) extraction from matte or copper, (3) dust treatment, (4) anode doping and (5) purification of electrolyte. Vacuum refining which is not established as a current industrial process is also described in this article.

Problems and Prospects of Halogen Element Contained Dust Treatment in Recycling

For processing the halogen element contained dust (for example, Electric Arc Furnace Dust and Auto Shredder Residue) generated at the time of recovery of valuable metals by the smelting furnace, the problem of EAF dust processing, such as comparisons of the present technology in pyro-metallurgy and hydro-metallurgy, behavior of the zinc volatilization in pyro-metallurgy, mechanism of the impurities accumulation in hydro-metallurgy, and de-halogen processing were described using computer simulation.

Study of the presence of fluorine in the recycled fractions during carbothermal treatment of EAF dust

Carbothermal treatment tests of electric arc furnace dusts (EAFD) using the Waelz kiln process were carried out in pilot-scale for the production of zinc oxide. The association of halides in the EAFD, and the recycled products, such as zinc oxide fumes and high-grade iron contents fractions were examined by X-ray diffraction (XRD), scanning electron microscope (SEM) and transmission electron microscope (TEM) analysis. XRD reveals the presence of chlorine and fluorine in the dusts in the form of KCl, NaCl and CaF 2. An ultra-pure fraction of zinc was obtained after the Double Leaching Waelz Oxide (DLWO) process was performed on the zinc oxide fumes. The halide contents were reduced to approximately 100 ppm Cl and 700 ppm F. The rest of these elements are in the form of CaF 2. About 65% F is volatilised as lead and zinc fluorides, 15% is expected in the magnetic fractions and 20% in non-magnetic fractions as CaF 2 and MnF 2, respectively.

Zinc solvent extraction in the process industries

The global zinc industry is currently experiencing unprecedented interest in new developments and expansions. While most of the new projects and plant upgrades remain committed to traditional processing technologies, recent advances in zinc solvent extraction have created opportunities for new process routes in the treatment of both primary ore and secondary materials. The production of special high-grade zinc from the complex Skorpion ore, previously considered untreatable, will be the first commercial application of zinc solvent extraction for the mainstream processing of primary ore. This mine-to-metal project promises to become one of the lowest-cost zinc producers. Solvent extraction is also under consideration for several other oxide and sulfide projects in various stages of feasibility. With respect to the processing of secondary materials, new applications of zinc solvent extraction have proved advantageous for the treatment of zinc residues and furnace dust. In contrast to the zinc industry itself, zinc solvent extraction is well established in the refining of other base metals, providing an efficient means of eliminating zinc as an impurity element. Many applications have been for cobalt and nickel refinery operations. More recently, larger-scale applications have been for primary operations, where refined copper, cobalt, and nickel are produced at the mine site. Previously regarded as a waste product in such operations, interest is now being shown in recovering zinc as a valuable by-product in selected flowsheets. The industrial application of zinc solvent extraction is reviewed in this paper. The reagents used for the selective extraction of zinc are discussed to provide the basic rationale for the choice of this separation technique. An historical perspective is given by brief discussions of some early applications. The review then focuses on recent installations and projects under development where zinc solvent extraction features as the key separation step.

Leaching of Zinc Oxide in Acidic Solution

Leaching mechanism of zinc oxide is important not only to understand zinc smelting process but also to develop of new zinc recycling process. Recycling of zinc is mainly done by treatment of electric arc furnace dust (EAF dust). In Japan pyro metallurgical process is enhanced for EAF dust treatment, however only zinc oxide can be recovered by pyro metallurgical process. Hydro metallurgical process makes it possible to recover high purity zinc directly from EAF dust. One of the main components of zinc included in EAF dusts is zinc oxide. Thus the mechanism of zinc oxide leaching is important to develop the new hydro metallurgical zinc recycling process. Leaching test of zinc oxide in hydrochloric acid and sulfuric acid solution has been carried out kinetically. Zinc oxide disk was used for leaching test which the reaction area is clear. The experimental parameters of pH, temperature, leaching time and rotating speed of the disk specimen were varied. The results obtained are as follows;\\ oindent(1) The activation energy of leaching reaction by sulfuric acid was 17.5 kJmol−1 and 11.6 kJmol−1 by hydrochloric acid solutions.\\ oindent(2) The leaching rate increases in proportion to the square root of rotating speed of test specimen.These results indicate that the rate controlling factor of zinc oxide leaching reaction in acidic solution is mass transportation.

Treatment of Copper Converter Flue Dust for the Separation of Metallic/Non-metallic Copper by Hydrometallurgical Processing.

To the CSIC (Spain) for support to carry out this work. To Cognis Corp. for supplying samples of the extractants.

Photospheric Properties of L and T Dwarfs

The photospheric spectra of all L and T dwarfs contain strong molecular bands and alkali absorption features, and those of L and early T dwarfs are also affected by dust. Although work on atmospheric models is addressing the treatment of dust, and is increasing the completeness of molecular opacity linelists, the effective temperatures of L and T dwarfs cannot be derived confidently from the modelled spectral energy distributions. However, because the radii of brown dwarfs older than 0.1 Gyr vary little with mass, measurements of intrinsic luminosity (i.e. total integrated flux and parallax) accurately determine effective temperature. Using this method we find a well constrained relationship between the effective temperatures of L and T dwarfs and spectral type, but with temperature nearly constant from L7 to T4. More work is required to determine the uniqueness of this relationship and to constrain the masses and ages of brown dwarfs.