Waste Zinc Research Articles

Optimization of sulfation roasting and water leaching for zinc recovery from zinc waste

Çinko atıkları çinko üretimi için ekonomik değere sahip bir kaynaktır. Ancak, aynı zamanda içerdiği ağır metaller nedeniyle tehlikeli atık olarak da sınıflandırılırlar. Bu çalışmada sülfatlayıcı kavurma ve su liçi koşullarının metal çözünürlüğüne (Zn, Pb, Fe ve Ca) etkisi araştırılmıştır. Çeşitli sıcaklarda ve sürelerde amonyum sülfatla yapılan kavurma testleri sonrasında, kavrulmuş her bir numunenin mineralojik yapısı incelenmiştir. Kimyasal analiz sonuçlarına göre atığın %16,6 Pb, %12,5 Zn ve %7,5 Fe içerdiği tespit edilmiştir. Amonyum sülfatla ile kavurma işlemi sonunda, atığın sahip olduğu ZnFe2O4 ve Zn2SiO4 yapılarının çinko sülfata (ZnSO4) dönüştüğü saptanmıştır. Proses ekonomisi ve enerji tasarrufu göz önüne alınarak, yaklaşık %91 oranında çinko geri kazanımı için optimum çalışma şartı, 1:2 (g:g) oranında atık/amonyum sülfat oranı, 625 ºC kavurma sıcaklığı, 4 saat kavurma süresi, 25 ºC liç sıcaklığı ve 2 saat liç süresi olarak belirlenmiştir. Bu şartlar altında kurşun çözünmediği, kalsiyum ve demirin çözünürlüklerinin sırasıyla %41,2 ve %16,8 olarak tespit edilmiştir.

Performance of cement mortar mixes containing fine reclaimed asphalt pavement aggregates and zinc waste

Cement mortar mixes were prepared to test the suitability of fine reclaimed asphalt pavement (FRAP) aggregates as a replacement for natural fine aggregates (NFA). With different amounts of NFA (25%, 50%, 75% and 100% by weight) replaced with FRAP aggregates, the mechanical qualities of the mortar mix deteriorated. To counteract this, jarosite – a waste from the zinc industry – was used as a partial replacement for cement (replacements of 5%, 10% and 15%). The jarosite improved the microstructural, mechanical and shrinkage properties. For example, compared with the control mix (100% NFA), the mix containing 25% FRAP aggregates showed a 5.5% reduction in hardened density and a 14% reduction in compressive strength. With the addition of 10% jarosite, there was an increase of 4.85% in hardened density and 7% in compressive strength with respect to the mix containing 25% FRAP aggregates. It is thus suggested that 10% jarosite is used when FRAP aggregates are used to make cement mortar mixes. A cost analysis was also performed. The findings of this work are expected to inspire rational mix design recommendations for mortar mixes including FRAP aggregates, as well as bringing environmental and economic benefits by reducing carbon dioxide footprints.

Effective utilization of dolomitic lead–zinc waste rock by replacing dolomite as flux in iron ore sintering process

Effective utilization of dolomitic lead–zinc waste rock by replacing dolomite as flux in iron ore sintering process

Influence of labor migration on rural household food waste in China: Application of propensity score matching (PSM)

Food waste has emerged as a critical global concern, with households identified as major contributors to this pressing issue. As the world grapples with sustainability challenges, addressing food waste in the context of rural labor migration is crucial for achieving broader sustainable development goals. However, there is still limited research regarding the relationship between labor migration and food waste. We utilized propensity score matching to analyze cross-sectional data collected from 1270 rural households in China. Labor migration led to significant increases of 37% in overall food waste and 35% in plant-based food waste, respectively. Furthermore, households with labor migration exhibited 29%, 31%, and 30 % higher energy, protein, and carbohydrate waste, respectively, compared to non-migration households. Regarding micronutrients, migration led to a 39% increase in iron waste, a 42% increase in zinc waste, and a 47% increase in selenium waste. The results of the categorical analysis indicate variations in the impact of labor migration on food wastage within rural households. Food wastage in rural households with chronic illness patients responds differently to labor migration. Moreover, labor migration predominantly affects households without courier services in villages, where dietary diversity plays a significant role. Understanding these variations is essential for crafting targeted interventions and policies to address food waste in different rural contexts. The policy implications of our study are crucial for addressing food waste and advancing sustainable development in rural China, where labor migration plays a significant role.

Copper And Zinc Mining Tailings as A Partial Replacement for Cement to Increase the Compressive Strength of Concrete

This study uses copper and zinc mining waste from mining activity as a partial substitute for cement in the concrete mix. This initiative seeks to strengthen the compressive strength of concrete. Copper and zinc waste can partially replace the cement content in concrete due to meeting the necessary physical and chemical requirements. In addition, these residues promote the formation of binders that improve the hydration of Portland cement. This approach improves the physical and mechanical properties of concrete and its durability. It also has economic and environmental advantages, as it uses copper and zinc waste from mining operations. Obtaining copper involves processing minerals from mines, which may contain copper oxides or sulfides. The rock is milled to obtain copper and zinc; these elements are separated using water, air, and other chemicals. The resulting by-products are stored in mining waste deposits that comply with current regulations. As for the research methodology, a deductive approach with applied orientation and a quantitative approach is followed. A retroactive data collection instrument is used to describe and explain the process. The optimal percentage of joint incorporation of copper and zinc residues from mining activity is around 10% and 5%, respectively. If you want to use only copper waste, you could reach up to 30%, while zinc waste can be incorporated in a maximum of 5%. In addition, it is observed that incorporating lead and zinc residues by 40% instead of cement increases compressive strength by 18%.

Evaluation and Current State of Primary and Secondary Zinc Production—A Review

This article presents the history of zinc, its production and demand. The quantity of zinc production, both primary zinc from ores and concentrates, and secondary zinc from scrap and zinc-rich waste, was discussed. A comprehensive economic analysis covers zinc prices in the years 1960–2021. The basic methods of obtaining zinc from ores, including pyrometallurgical (Imperial Smelting Process ISP, Kivcet, Ausmelt) and hydrometallurgical (roasting–leaching–electrowinning RLE, atmospheric direct leaching ADL, Engitec Zinc Extraction EZINEX, zinc pressure leach) and their short characteristics, are presented. The global zinc market and the main areas of its application were analyzed. Technologies used for the recovery of zinc from scrap are discussed along with their characteristics. Galvanized steel is the main source of secondary zinc, both in the galvanizing process and in the remelting of galvanized steel. It can be easily recycled with other scrap steel in the electric arc furnace (EAF) for steel production. Currently, with high volatility in the price of zinc, as well as its natural resources in the earth’s crust, recycling is an important activity, despite the fact that zinc concentrates have a relatively constant chemical composition, while the resulting zinc waste contains zinc in varying amounts.

Transformasi Abu Vulkanik dan Limbah Seng menjadi Nanokomposit ZnO-SiO2 dan Aplikasinya untuk Degradasi Rhodamin B

Rhodamine B is a non-biodegradable organic pollutant that is difficult to decompose by microorganisms. If it is possible to be degraded it will take a long time. The semiconductor used is ZnO using SiO2 host material. The reason for using SiO2 is that apart from high efficiency, there are also abundant raw materials because the eruption of Mount Merapi occurs regularly every 4 years. The high content of SiO2 in volcanic ash can be utilized and processed into silica gel through the formation of potassium silicate resulting from the reaction between SiO2 in volcanic ash and potassium hydroxide. In addition to the presence of abundant SiO2, ZnO sources from lathe workshop waste are also easily obtained. The manufacture of ZnO/SiO2 nanocomposites was carried out using the sol – gel method because it is easy and has high effectiveness. ZnO/SiO2 nanocomposite was applied as an adsorbent to degrade Rhodamine B. This study aims to determine the character of ZnO/SiO2 nanocomposite and to determine the best conditions for optimal degradation. Synthesis of ZnO/SiO2 nanocomposite based on volcanic ash and zinc waste resulted in a composite size with a size range of 100-200 nm and a uniform circular shape. The results of the FTIR test show that SiO is at a wavelength of 993.34 and 1109.07 cm-1, while ZnO is at a wavelength of 443.63 cm-1. The XRD results of ZnO/SiO2 nanocomposite are known to peak at 2𝜃, namely 30.42o, 31.56o, and 44.40o. The application of dye degradation on UV irradiation, as well as looking for pH, time, and concentration gave the maximum Rhodamine B degradation value. The results of this study indicate that the highest efficiency in decreasing the concentration of Rhodamine B was obtained at pH 3 with a contact time of 60 minutes and a concentration of Rhodamine B of 10 ppm. The degradation efficiency of Rhodamine B obtained under these conditions is 95.8690%. Based on the concentration variation data processing using the Langmuir isotherm equation, it is known that the adsorption capacity of Rhodamine B is 97.3458521%.

Growth, nutrient retention, wastes output and nonspecific immunity of juvenile snakehead Channa argus in response to dietary zinc levels

An 8-week feeding trial was conducted to investigate the effects of dietary zinc levels on growth, nutrient retention, waste output and nonspecific immunity of juvenile snakehead Channa argus. Six isonitrogenous (485 g/kg crude protein) and isolipidic (106 g/kg crude lipid) diets were formulated, with supplementation of graded levels of hydrated zinc sulphate at 0 (diet Zn0), 0.2 (diet Zn0.2), 0.4 (diet Zn0.4), 0.7 (diet Zn0.7), 1.0 (diet Zn1.0) and 1.3 g/kg (diet Zn1.3), which provided the actual dietary zinc concentration of 56, 99, 140, 235, 301 and 375 mg/kg respectively. The highest weight gain rate was found in fish fed diet Zn0.7. Lower feed intake and feed conversion ratio, while higher retention efficiencies of nitrogen and phosphorus, were found in fish fed diets Zn0.2, Zn0.4 and Zn0.7 than in fish fed diets Zn0 and Zn1.3. Zinc retention efficiency decreased with the increase IN dietary zinc levels. Contents of zinc in whole body and spinal bone increased with dietary hydrated zinc sulphate increased from 0 to 0.7 g/kg. Higher nitrogen and phosphorous waste were found in fish fed diets Zn0, Zn1.0 and Zn1.3 than in fish fed diets Zn0.2, Zn0.4 and Zn0.7, and lower zinc waste was found in fish fed diets Zn0, Zn0.2, Zn0.4 and Zn0.7 than in fish fed diets Zn1.0 and Zn1.3. Higher serum C4 and IgM were found in fish fed diets Zn0.7, Zn1.0 and Zn1.3 than in fish fed diet Zn0, Zn0.2 and Zn0.4. Our results showed that dietary supplementation of hydrated zinc sulphate needed to promote fast growth, keep good nutrient retention and immunological capacity, and reduce waste discharge in juvenile snakehead should be 0.7 g/kg (235 mg/kg zinc concentration).

An Experimental Investigation of the Environmental Risk of a Metallurgical Waste Deposit

The aim of this study is to investigate the environmental risk of long-term metallurgical waste disposal. The investigated site was used for the open storage of lead and zinc waste materials originating from a lead smelter and refinery. Even after remediation was performed, the soil in the close vicinity of the metallurgical waste deposit was heavily loaded with heavy metals and arsenic. The pollutants were bound in various compounds in the form of sulfides, oxides, and chlorides, as well as complex minerals, impacting the pH values of the investigated soil, such that they varied between 2.8 for sample 6 and 7.34 for sample 8. In order to assess the environmental risk, some eight soil samples were analyzed by determining the total metal concentration by acid digestion and chemical fractionation of heavy metals using the BCR sequential extraction method. Inductively coupled plasma optical emission spectrometry (ICP-OES) was used to determine six elements (As, Cd, Cu, Pb, Zn, and Ni). Total concentrations of the elements in the tested soil samples were in the range of 3870.4–52,306.18 mg/kg for As, 2.19–49.84 mg/kg for Cd, 268.03–986.66 mg/kg for Cu, 7.34–114.67 mg/kg for Ni, 1223.13–30,339.74 mg/kg for Pb, and 58.21–8212.99 mg/kg for Zn. The ratio between the mean concentrations of the tested metals was determined in this order: As > Pb > Zn > Cu > Ni > Cd. The BCR results showed that Pb (50.7%), Zn (49.2%), and Cd (34.7%) had the highest concentrations in mobile fractions in the soil compared to the other metals. The contamination factor was very high for Pb (0.09–33.54), As (0.004–195.8), and Zn (0.14–16.06). According to the calculated index of potential environmental risk, it was confirmed that the mobility of Pb and As have a great impact on the environment.

Pengaruh Penambahan Serbuk Seng (Zno Powder) Terhadap Berat, Kuat Tekan Dan Kuat Tarik Belah Beton

Indonesia is a developing country that has quite advanced industrial prospects, one of which is the zinc industry. Increased zinc production, will also increase zinc waste. Based on the nature of ZnO which readily reacts with other compounds, this compound can be used as a mixture in making concrete so that it can produce quite good structural strength. This study aims to determine how the effect of using zinc powder on weight, compressive strength and split tensile strength of concrete. The variations in the addition of zinc powder consisted of 0.25%, 0.5%, 0.75% and 1% by weight of the cement used. The test object used is a cylinder with a size of 15 cm x 30 cm. Tests for weight, compressive strength and split tensile strength were carried out when the concrete was 28 days old. The results obtained are for the weight of concrete with variations in the addition of zinc powder as much as 0%, 0.25%, 0.75% and 1% respectively of 2294 Kg / m3, 2305 Kg / m3, 2311 Kg / m3, 2305 Kg / m3, 2323 Kg / m3. Meanwhile, the compressive strength is 30.49 MPa, 30.356 MPa, 32.92 MPa, 32.69 MPa and 31.573 MPa. And for the tensile strength of concrete with the same variations, namely 11.306 MPa, 10.597 MPa, 11.976 MPa, 13.07 MPa and 13.426 MPa.

The Influence of Zinc Waste Filler on the Tribological and Mechanical Properties of Silicone-Based Composites.

Silicones are often used for various types of coatings, but due to their poor mechanical properties, they often require modification to meet specific requirements. At the same time, various production processes throughout the world generate different types of waste, the disposal of which is harmful to the environment. One possible solution is to use production waste as a filler. In this paper, the authors investigated how the use of metallurgical production waste products as fillers changed the mechanical properties of silicone composites prepared by casting. Composite samples were characterized using tensile tests, resilience, pin-on-disc, Schopper–Schlobach abrasion, hardness, and density measurements. Based on the obtained results, the authors assessed the effect of each of the fillers used in different weight proportions. The results showed that the silicone composite filled with 5 wt% zinc dust showed the lowest decrease in tensile strength and Young’s modulus, with a simultaneous significant reduction in abrasion compared with the reference sample. This research shows that zinc waste can be successfully introduced into a silicone matrix in cases where it is important to reduce abrasive wear.

Synthesis and Characterization of SiO2/ZnO Nanocomposites from Zinc Waste and Mount Merapi Volcanic Ash

Research on the synthesis and characterization of SiO2/ZnO nanocomposites from zinc waste and Mount Merapi volcanic ash has been carried out. The semiconductor used was ZnO using a SiO2 as the host material. The use of SiO2 was due to its high efficiency and abundant raw materials. This is because the eruption of Mount Merapi occurs regularly every four years. Apart from the abundant presence of SiO2, the source of ZnO from lathe workshop waste is also easy to obtain. The research aims to reduce the volume of zinc waste from the lathe and volcanic ash, which was not optimized. Zinc waste and volcanic ash were synthesized into nanocomposites. Then the obtained nanocomposites were characterized to determine their effectiveness in degrading various wastes. The synthesis of SiO2/ZnO nanocomposites was carried out using the sol-gel method as easy and highly effective. The method used is to transform zinc waste into Zn(OH)2. The volcanic ash was extracted with KOH to form potassium silicate (K2SiO3). Zn(OH)2, (K2SiO3) and HCl were reacted together when sonicated, then calcined at 550°C. The results showed that SiO2/ZnO nanocomposites made from volcanic ash and zinc waste produced composite sizes with a size range of 100-200 nm and a uniform circular shape. FTIR analysis results show that SiO has the peaks at wavenumbers of 993.34 and 1109.07 cm-1, while the ZnO peak is at wavenumbers of 443.63 cm-1. The XRD diffractogram of SiO2/ZnO nanocomposites shows peaks at 2θ of 30.42°, 31.56°, and 44.40°.

Characterization of Activated Coconut Shell Charcoal as a Zinc Absorbent for Used Oil Lubricant

Lubricating oil is classified as B3 waste (hazardous and toxic waste). In the lubricating oil consists of zinc waste which is very dangeraous for healt and environment. So that to handle lubricating oil is used the adsorption method using coconut shell as adsorbent. This study aims to determine the efficiency of zinc adsorption on lubricating oil with stirring speed, percent solvent, mesh size, and mass of adsorbent variation; to learn the equibilium equation of adsorpsion of Zn metal ion on the activated carbon of coconut shell charcoal using Freundlich and Langmuir equilibirium; and to calculate adsorbtion kinetic constanta using the pseudo first model or pseudo second order kinetics approach. Coconut shells was heated at a temperature of 300ᴼC for 1 hour for the driving process . Furthermore, charcoal was soaked in 25% HCl for 18 hours. After being neutralized to pH 7, the charcoal was activated for 3 hours at a temperature of 500ᴼC and stored in a closed place. Coconut shell adsorbent and H2SO4 solvent were put into a beaker glass containing 400 ml of lubricating oil and stirred for 2 hours, every 30 minutes intervals were taken 50 ml to destruction for 2 hours with 68% HNO3. The zinc concentration before and after adsorption were measured using AAS. This study uses the Langmuir isotherm and Freundlich Isotherm models. The greatest efficiency of zinc adsorption with solvent percent variation 0.5% is 95.0567% and 99.9375% in adsorbent mass variation of 10 gram.

Zinc Waste as a Substitute for Portland Cement in Roller-Compacted Concrete Pavement Mixes Containing RAP Aggregates

AbstractOwing to heavy toxic metal concentration such as copper, lead, zinc, sulfur, cadmium, and chromium, jarosite particles from the zinc industry are considered a hazardous waste material. Prop...

Use of Modified Acasia arabica Tree Bark Substrate for the Adsorption of Ni (II) From Aqueous Solution

Salt of various metals and other potentially dangerous are being discharged in to the aquatic environment, water containing vital concentration of some of the heavy metal ions are harmful to human being, animal as well as aquatic organism. The toxicity of some heavy metal ions even at the trace level has been recognized with respect to public health for many years. Metals such as Mercury, Lead, Cadmium, Copper, Nickel and Chromium are under this category. Many metals have been evaluated as harmful to aquatic life above certain toxicity level. Many industries may have specific waste problem where the particular metal is an integral part of the many manufacturing process. Notable examples are the high zinc waste of viscosity Rayon manufacturing ground wood pulp production and News print production. Adsorption has been proved to be an excellent way to treat industrial waste effluents, offering significant advantages like the low-cost availability, profitability, ease of operation and efficiency comparative to activated carbon. The Acasia arabica tree bark substrate was found to have good sorption capacity for Nickel. Studies indicate that the sorption of Ni (II) increases with the increase in pH value and contact time, 30minute was found to be optimum. The effect of concentration shows that the Acasia arabica can remove Ni (II) ions from aqueous solutions, the concentration of metal ions increases adsorption decreases.

Environmental impact assessment of galvanized sheet production: a case study in Shandong Province, China

Galvanized sheet is the most widely used coated steel plate globally in the industry of construction, automobile, electronics manufacturing, etc. Large amounts of resources and energy are used in galvanized sheet production, which likewise generates vast amounts of pollutant emissions. In the face of the rapid growth of the production and demand of galvanized sheet in China, it is very important to find out the key factors of the environment impact in the production of galvanized sheet. An evaluation of the environmental impact of galvanized sheet production in China was conducted by using the framework of life cycle assessment to improve resource saving and environmental protection in the galvanized sheet industry, and update the life cycle inventory database of galvanized sheet production. The environmental impact assessment was carried out based on the life cycle assessment framework by the use of ReCiPe 2016 method which was applicable on a global scale to evaluate the environmental impact of galvanized sheet production. Methods of uncertainty analysis and sensitivity analysis were adopted to provide credible support. The midpoint categories of global warming and fossil resource scarcity, as well as the endpoint categories of human health contributed most to environmental burden, which were mainly caused by carbon dioxide emissions and coal consumption. Environmental impact was dominated by the key process of continuous casting billet production, followed by electrolytic zinc production and electricity generation. Additional CO2-reducing measures should be implemented in galvanized sheet production to slow the effect of global warming. Moreover, biomass char reducing agents, rather than coal-based reducing agents, should be utilized in steelmaking to reduce fossil resource consumption. Furthermore, renewable energy, rather than coal-based electricity, should be used in galvanized sheet production to reduce carbon emissions and fossil resource consumption. Increasing the recycling rate of scrap steel and zinc waste can save resources and reduce environmental burden. The results of this study can provide guidance in the reduction of resource consumption and environmental burden of galvanized sheet production to the maximum extent.

Characterization and mobilization of toxic metals from electrolytic zinc waste

The natural and forced mobilization of lead, cadmium and arsenic in zinc hydrometallurgy waste is studied with the purpose of establishing potentially environmentally damaging levels and associated risks in uncontrolled situations. Differential X-Ray diffraction is used to study, in simulated environmental situations, the relevant role played by several mineralogical and amorphous phases. The study of potential mobility shows that all the samples considered are susceptible of releasing a significant amount of potentially toxic elements (PTEs) depending of the particular environmental conditions. Two situations can be considered the most problematic: the natural mobilization of the released cadmium and zinc as a result of rain, and a change in the redox conditions caused by an anoxic environment (flooding and/or incorporation of organic matter). The presence of massive quantities of soluble salts increases the hazard potential of these residues, mobilizing the PTEs and creating a potential carcinogenic risk caused by a possible oral intake for both children and adults.

Removal of copper from cattle footbath wastewater with layered double hydroxide adsorbents as a route to antimicrobial resistance mitigation on dairy farms

Copper and zinc are routinely used in livestock antimicrobial footbaths in commercial farming. The footbath mix is a cost to farmers, and the disposal of spent footbath into slurry tanks leads to soil contamination, as well as the potential for antimicrobial metal resistance and co-selection. This study assesses the potential to mitigate a source of antimicrobial metal resistance in slurry tanks while recovering copper and zinc from spent cattle footbaths. This is the first study in literature to investigate the potential of recovering copper from cattle footbath solutions via any method. The sorbent, Ca2Al-EDTA Layered Double Hydroxides (LDH), were used to remove Cu2+ from a Cu2SO4·5H20 solution at different temperatures. The maximum Cu2+ uptake from the Cu2SO4·5H20 solution was 568 ± 88 mg g−1. Faster and higher equilibrium uptake was achieved by increasing the temperature of the solution. The sorbent was found to be effective in removing copper and zinc from a commercially available cattle footbath solution (filtered footbath solution Cu2+ uptake 283 ± 11.05 mg g−1, Zn2+ uptake 60 ± 0.05 mg g−1). Thus, this study demonstrates the opportunity for a completely novel and potentially economically beneficial method of mitigating antimicrobial resistance in agriculture and the environment, while also providing a new valuable copper and zinc waste stream for secondary metal production.

Study of ants as bioindicators of industrial pollution in Kemerovo Region, Russia

The myrmecocomplexes of five industrial cities in the territory of Kuzbass, Russia, were studied. The general trends in the reaction of ants to the pollution by gaseous (chemical industry) and solid (coal and cement dust, lead and zinc waste and metallurgical industry) emissions were revealed. It was found out that the proportion of species of subfamilies, species richness and density of the settlement can be used as bioindicators. The predominance of L. niger and M. rubra nests in myrmecocomplexes immediately indicates a high degree of man-made impact.

Comparative studies on acid leaching of zinc waste materials

Three industrial waste materials were characterized in terms of their elemental and phase compositions, leaching behaviour in 10% sulfuric acid solution as well as leaching thermal effects. Slag from melting of mixed metallic scrap contained about 50% Zn and 10% Pb. It consisted mainly of various oxides and oxy-chlorides of metals. Zinc spray metallizing dust contained about 77% Zn in form of zinc and/or zinc-iron oxides, zinc metal and Zn-Fe intermetallic. Zinc ash from hot dip galvanizing was a mixture of zinc oxide, metallic zinc and zinc hydroxide chloride and contained about 80% Zn. Dissolution efficiency of zinc from the first material was 80% (independently on the solid to liquid ratio, 50–150 kg/m3), while decrease of the efficacy from 80% to 60% with increased solid to liquid ratio for the two remaining materials was observed. Both increase in the temperature (20 °C to 35 °C) and agitation rate (300 rpm to 900 rpm) did not improve seriously the leaching results. In all cases, transfer of zinc ions to the leachate was accompanied by different levels of solution contamination, depending on the type of the waste. Leaching of the materials was exothermic with the similar reaction heats for two high oxide-type products (slag, zinc ash) and higher values for the spray metallizing dust.