Leaching Of Slag Research Articles

Leachate and contact test with Lepidium sativum L. to assess the phytotoxicity of waste

The study evaluated the use of Lepidium sativum L. to assess the phytotoxicity of three types of waste such as hazardous waste (slags from zinc to copper smelters) and nonhazardous waste (mineral–organic composite). Previous studies evaluated heavy metal leaching and the environmental impact of the tested waste. The purpose of phytotoxicity studies was to increase knowledge about this waste. Two types of tests were used to assess the phytotoxicity of wastes: germination index and accumulation test. Both tests were carried out for leachate (leachate test) and waste (contact test). The results of both tests were compared to assess the phytotoxic effects of tested waste. Phytotoxicity tests have shown that the mineral–organic composite leachate was stimulated plant growth, copper smelter slag leachate was characterized by no phytotoxicity and zinc slag leachate inhibited the growth of plants. In contrast, contact test showed inhibitory effects from all tested waste. Wherefore, the contact test was indicated as more sensitive in the assessment of phytotoxicity. However, this is not a clear assessment, because the germination index values for both tests were a result of differences of root length for both control samples (deionized water and sand). The study confirmed the usefulness of L. sativum for the assessment of phytotoxicity of various types of waste. Additionally, it was found that L. sativum was resistant to high concentrations of heavy metals in the leachate, without causing any negative physiological effects.

Composite plates utilizing dealkalized red mud, acid leaching slag and dealkalized red mud-fly ash: Preparation and performance comparison

Dealkalized red mud, fly ash and acid leaching slag served as reinforcements to prepare composite plates by a molding method using an open mill and vulcanizing press. The optimal dosage of dealkalized red mud, acid leaching slag, and dealkalized red mud-fly ash was 40 wt%, 30 wt%, and 40 wt%, respectively, and the modifying agent aminopropyl triethoxysilane content was 3 wt%. The tensile strength and bending strength of the prepared composite plates were 23.5 MPa and 28.7 MPa, respectively, and the limiting oxygen index was 27.3%. Moreover, in order to improve electromagnetic performance and thermal conductivity of the composite plate, carbon powder, graphene and graphite ores were added to the composite plate respectively when dealkalized red mud-fly ash served as filler. It is found that the absorption peak decreased to −21.45 ranging from 9 to 12 GHz in the composite plate with graphene. SEM observation indicates that there is effective combination between the filler of dealkalized red mud-fly ash and PP in the composite plate. The manufacturing process of composite plate has less environmental impact and lower production cost. It could be applied to the field of construction, such as decorative panels and tubular products potentially.

Efficiency of Chemical and Biological Leaching of Copper Slag for the Recovery of Metals and Valorisation of the Leach Residue as Raw Material in Cement Production

Copper slags produced in vast quantities in smelting operations could be considered as secondary material sources instead of stockpiling them in landfills. This study investigates the recovery of valuable metals from copper slag and the valorisation of the leach residue as construction material in line with the principles of a circular economy. By taking into account that the environmental characterization of the as-received copper slag did not allow its disposal in landfills without prior treatment, chemical and biological leaching were tested for the recovery of metals. Pre-treatment with acids, namely HNO3 and H2SO4, resulted in the extraction of several target metals and the production of an almost inert waste. Despite the clearly better oxidative conditions prevailing in the bioleaching reactors, chemical leaching resulted in the higher dissolution of Cu (71% vs. 51%), Co (70% vs. 36%), and Zn (65% vs. 44%). The acid consumption was much lower during the bioleaching experiments compared to the chemical leaching. The bioleach residue was suitable for its use as supplementary cementitious material, showing a better performance than the reference sample without causing any detrimental effects to the calcium aluminate cement (CAC) quality. The complete valorisation of copper slags is expected to improve the economics of the process, by avoiding landfill costs and producing saleable products with high added value.

Performance evaluation and process simulation for synergetic removal of NOx, CO2 and PM using green alkaline solution in a high-gravity rotating packed bed

The high-gravity rotating packed bed (HiGee RPB) developed here can simultaneously remove multiple air pollutants using alkaline solution, thus achieving the flue gas deep purification. The electric-arc-furnace reduction slag (EAFRS) leachate was then used as the alkaline absorbent in HiGee RPB for assessing the removal efficiencies of nitrogen oxide (NOx), carbon dioxide (CO2) and particulate matters (PM) from flue gas. The results indicated the changes to the CO2 capture was enhanced by increasing the initial PH value of the alkaline solution. In contrast, this value has no significant influence on NOx removal. The suitable NOx removal efficiency ranged from 90.9% to 97.09% at the liquid-to-gas (L/G) ratio of 0.01 and high gravity factor of 58.9 to 368. The precipitated calcium carbonate gained from carbonation via HiGee process exhibited similar physical properties to commercial products. In addition, 95.9% of PM removal efficiency was achieved at the L/G ratio and high gravity factor of 0.03 and 235.4, respectively. This treatment furthermore demonstrated a high efficiency for PM collection of over 90% and balanced the energy consumption. Based on the result, an Aspen simulation and a preliminary cost-benefit analysis were carried out to develop a mass-balance model for this system and determine the favorable operating conditions.

Ammoniacal System Mechanisms for Leaching Copper from Converter Slag

In pyrometallurgical processes refining copper, the main source of loss in the conversion stage is from slag. This paper reports on research work treating converter slag containing high percentages of copper (36 wt%) using ammonium hydroxide at room temperature. Variables analyzed are solution pH, agitation, temperature, NH4OH concentration and particle size. Results showed that the hydronium ion resulting from ammonium hydroxide dissociation was the main oxidant of copper compounds in slag, such as CuO, Cu2O and Cu, with the exception of CuFeO2. The particles contain a large amount of microcracks (porosity) in their refractory structure (analyzed by compositional image capture (BSE)). Thus, the diffusion of the leaching solution through the microcracks making contact with the copper oxides would be allowed. Leaching mechanisms were corroborated by X-ray diffraction and scanning electron microscopy analysis. Increasing temperature and NH4OH concentration while decreasing particle size obtained higher copper recoveries, reaching values of 84.8%. Under the same conditions, the main impurity (iron) was minimal (<2%). Solution pH also affected slag leaching. Agitation of the solution positively affected the rate of copper extraction. Leaching kinetics of the leaching solution through the porosity formed in the slag was analyzed under the intraparticle diffusion model. The reaction order was 1.2 with respect to the concentration of ammonium hydroxide and the model was inversely proportional to the square of the particle radius. The activation energy obtained was 42.3 kJ/mol for temperature range 283 to 333 K.

Recycling and utilization of high volume converter steel slag into CO2 activated mortars – The role of slag particle size

Converter steel slag is produced in large quantities as by-product of primary steel-making, which is mainly landfilled or used as an aggregate The high reactivity of converter steel slag with CO2 makes it an ideal material for CO2 capture by forming calcite even at ambient temperature and pressure. This reaction can also be used to for the production of green building materials. However, the carbonation of steel slag is strongly controlled by the particle size, which influences CO2 transport and carbonation speed. In this study, low carbon footprint binders consisting of various fine converter steel slag powder (80%) and normal cement (20%) are applied to produce mortars using ambient carbonation. The results indicate that the variation of steel slag particle size influences gas transport and CO2 uptake of carbonated steel slag blended mortars during the curing period, which effects microstructure, strength, and leaching. The application of optimal size range of steel slag (21.75–24.13 µm) in blended mortars leads to a higher compressive strength (31.21 MPa), CO2 uptake (15.9 %), faster carbonation rateas well as sustainability efficiency (0.486 MPa/(kg/m3)), which is obviously superior compared to the larger or smaller size of steel slags mortars. . The leaching properties, especially V and Ca leaching of steel slag blended mortars are observed to be strongly influenced by the CO2 uptake, rather than steel slag particle size. A green binder system is achieved by both the reduction of cement content and the high CO2 uptake by mass of binder.

Applying steel slag leachate as a reagent substantially enhances pH reduction efficiency for humidification treatment.

A cost-effective, easy-to-implement, and sustainable approach is needed to mitigate the production of alkaline leachate from steel slags that are reused or disposed in the environment. To address this issue, a humidification treatment process, which is operated by wetting a stack of steel slag using aqueous reagents and letting atmospheric CO2 to be passively diffused into the slag pores to induce slag carbonation reaction, was previously developed. In this study, we demonstrate that the leachate of raw steel slag can be recycled and used as a humidification reagent to substantially enhance the treatment efficiency as well as to enable operating the process with neither synthetic chemical consumption nor wastewater discharge. In a 24-h study, a 0.61-unit reduction in slag pH is achieved using a raw slag leachate as a reagent, which is substantially greater than a 0.28-unit reduction using deionized water. The net amount of CaCO3 produced during an extended humidification duration of 4weeks is increased by 2.7-fold when the leachate is used instead of deionized water. A series of systematically designed experiments demonstrates that the pH (11.0) and ionic strength (0.0048) are the two major characteristics of the raw slag leachate that contribute to the enhanced efficiency of humidification treatment. With further demonstration at larger scales in follow-up studies, the novel humidification process that utilizes the leachate generated on-site as a reagent is expected to be a feasible alternative for alkali waste treatment prior to its reuse or disposal.

Reverse leaching of magnesium from ferronickel slag using alkali solvent NaOH

A research based on magnesium extraction of ferronickel slag waste processed by reverse leaching using sodium hydroxide (NaOH) solutions has been carried out. The ferronickel slag has the main compositions of magnesium silicate and iron silicate. The early procedure of the research was the preparation of ferronickel slag grinding using a ball mill until it gets a size of –200 mesh. Secondly, the calcination of ferronickel slags to remove crystal water and increase the size of the porosity so that it would facilitate the leaching process. The next procedure was reverse leaching using sodium hydroxide (NaOH) to dissolve silica. By dissolving the silica, it was expected that the contents of elements such as magnesium and iron would increase in the residue. The variations in this ferronickel slag leaching research were leaching time, solvent concentration and leaching temperature. The reverse leaching of ferronickel slag was carried out with a time variation of 15 to 240 minutes, the temperature of 30 °C, 70 °C, and 100 °C and NaOH concentrations are 9 M, 10 M, and 11 M. The XRD (X-ray diffraction) analysis, (XRF X-ray fluorescence) analysis, SEM (Scanning Electron Microscope) analysis, and ICP-OES (Inductively Coupled Plasma) analysis were used to observe the initial characteristics of the ferronickel slag and the results after the leaching process. The characterization result towards ferronickel slag samples by XRD analysis shows that the compositions of the dominant compounds are forsterite (Mg 2 SiO 4 ), enstatite (MgSiO 3 ) and fayalite (Fe 2 SiO 4 ). Moreover, the result is also supported by XRF analysis and SEM mapping analysis. The quantitative analysis of XRF shows that ferronickel slag contains 45.69 % of SiO 2 , 29.32 % of MgO and 16.5 % of Fe 2 O 3 . The results of the SEM mapping analysis show that Mg, Si, Fe and O bond together that indicates the presence of magnesium silicate and iron silicate. The highest percentage of magnesium extraction is 73.10 % under experimental temperature conditions of 100 °C for 240 minutes, 10 M of solvent concentration and 300 rpm of stirring speed. Increasing percentage of magnesium extraction is caused by the dissolution of silica in the leaching process. The dissolution of silica is proved by the existence of magnesium hydroxide and iron(II) hydroxide in the residue that is shown by the XRD analysis. It resulted in the MgO content in the residue increase significantly to 42.8 % as shown by the XRF analysis. Moreover, the SEM mapping analysis shows that Mg and O bond together that indicated the presence of MgO. It also can be determined that MgO is dominant

Optimization of Tellurium and Antimony Extraction from Residue Generated in Alkaline Sulfide Leaching of Tellurium-Bearing Alkaline Skimming Slag Using Central Composite Design

A possible process for extracting tellurium and antimony from a residue generated in alkaline sulfide leaching of tellurium-bearing alkaline skimming slag was proposed. The central composite design was employed to define the optimal leaching conditions for tellurium and antimony extractions from the residue sample. Using a 23 factorial matrix, the best performance for tellurium and antimony extractions (96.36% and 99.64%) were obtained at 175 g L−1 Na2S concentration for 80 °C during 60 min. The notable degree for influencing tellurium and antimony extractions was leaching temperature, Na2S concentration, and leaching time. The analysis of variance results indicated that the regression model was significant and suitable to be used for the optimization of independent variables within the range. The model was validated under optimal operating conditions based on the experimental design results. Antimony and tellurium in the leach liquor were separated and recovered by H2O2 oxidation followed by Na2S-Na2SO3 reduction. 98.93% of antimony was precipitated selectively during H2O2 oxidation, while 95.06% of tellurium was precipitated during Na2S-Na2SO3 reduction. NaSb(OH)6 and elemental tellurium was obtained as the product.

Dielectric properties and microwave heating behavior of neutral leaching residues from zinc metallurgy in the microwave field

AbstractThe method of microwave strengthens roasting neutral leaching slag contained germanium is put forward. The dielectric properties and temperature rising behavior of neutral leaching slag in the microwave field are analyzed via experimental and theoretical analysis. The experiment used the dielectric constant test device, the microwave roasting device and the temperature measuring device. The neutral leaching slag can absorb microwave energy and transform into heat energy. The specific surface area of the calcined slag containing the neutral leaching slag is increased by microwave roasting, and the microwave energy can reduce the particle size of the mineral particles to some extent. At the same time, cracks can be seen on the surface of the calcined sand after microwave roasting. The surface of neutral leaching slag roasted by microwave reformed cracks which help to open reaction channels making the oxygen to inside takes part in oxidizing reaction significantly improving germanium oxide reaction conditions, besides increasing the leaching process of the reaction area and increasing the leaching rate. The research on the dielectric constants and temperature characteristics of neutral leaching residue can provide the theoretical and experimental basis for microwave strengthen roasting.

Pressure Sulfuric Acid Leaching of Manganese-Rich Slag with Pyrite as Additive

Large amounts of manganese-rich slag were generated from smelting low-grade manganese ore containing high iron and high phosphorus in electric furnace or blast furnace, which contain 25–40 mass% Mn. This paper describes an efficient hydrometallurgical process for the utilization of high manganese slag instead of conventional usage of pyrometallurgical route for manganese recovery. Pressure acid leaching of manganese-rich slag using air as pressurized gas is studied systematically. The effects of mass ratio of manganese-rich slag to pyrite, concentration of sulfuric acid, leaching temperature, partial air pressure, leaching time, and liquid-solid (L/S) ratio on the separation of manganese with other main impurity components were investigated comprehensively. Under the following optimal process conditions, weight of manganese-rich slag powder,100 g; mass ratio of manganese-rich slag to pyrite, 20:1; sulfuric acid concentration of 140 g/L; air pressure of 0.6 MPa; leaching temperature of 140 °C; leaching time of 1 h; L/S of 7:1; ore size of 75–80 μm; and stirring rate of 600 rpm, the extraction rate of Mn reached 94%, and the dissolution percentage of Si, Al, and Fe are as low as 2%, 6%, and 10%, respectively. The leaching slurry presented a good solid-liquid separation characteristic. The silicic acid formed during sulfuric acid leaching manganese silicates was converted to filterable dehydrated SiO2 particles which precipitated in the residue under the condition of higher temperature with higher pressure. The effect of adding pyrite may be to reduced iron ions and decreased the output of iron hydroxide colloid and also reduced MnO2 to manganese sulfate in sulfuric acid leaching. Thus the formation possibility of colloid such as silica gel and iron hydroxide was decreased, and higher yield of manganese sulfate could be achieved.

Leaching behavior of copper slag aggregate cement-mortar by atomic absorption spectroscopy (AAS)

Leaching behavior of copper slag aggregate cement mortar was analysed using atomic absorption spectrometry (AAS)with different mix proportion immersed in two aqueous fluids: conventional water and ammonia nitrate solution. Four types of cement-mortar mix i.e. M-type, S-type, N-type and O-type were cast with constant water/cement ratio to study the leaching effect with total replacement of natural fine aggregate with copper slag. Compressive strength test of hydraulic cement-mortar along with sorptivity test of all cement-mortar mix was also conducted. Experimental results of leaching study showed minimal leaching of copper slag incorporated cement-mortar for all proportion after 95 days of subjection to two aqueous fluids. Improved compressive strength was observed for all types of cement-mortar mix and also found to be increased with higher curing age. Rate of water absorption was found to be decreased with increased content of copper slag in cement-mortar for all mix proportion.

Ammonia leaching of slag from direct-to-blister copper smelting technology

Smelting of copper concentrates in a flash furnace directly into a copper blister results in the production of slag with high copper and lead content. The recovery of these metals is carried out in an electric furnace, from which copper–lead–iron metallic alloy is then processed in a converter furnace. In the presented work, copper and lead extraction studies were carried out by hydrometallurgical route under leaching in ammonium acetate solutions. The obtained results indicate the possibility of receiving quite high copper leaching efficiency from slag with a relatively low yield for lead extraction. The use of ammonium acetate solutions with a concentration of 5 mol/dm3 leads to leaching from the slag over 80% of the copper contained in it after 90 min of the process carried out at a temperature of 70 ℃. Model calculations related to the study of the kinetics of the process indicate that after 120 min of leaching it can be expected that 90% of the copper contained in the slag could be carried out into the solution.

An Innovative Technique for Comprehensive Utilization of High Aluminum Iron Ore via Pre-Reduced-Smelting Separation-Alkaline Leaching Process: Part I: Pre-Reduced-Smelting Separation to Recover Iron

In this study, a novel process was established for extraction of Fe and Al from a complex high aluminum iron ore (33.43% Fetotal and 19.09% Al2O3). The main steps in the proposed process included pre-reducing high alumina iron ore and subsequent smelting to produce pig iron and rich-alumina slag, followed by alkaline leaching of the slag to obtain sodium aluminate solution and a clean slag. When smelting the pre-reduced high alumina iron ore pellets at 1625 °C for 30 min with a slag basicity of 0.40, the pig iron yielded 97.08% Fe and extracted 0.13% Al2O3, together with an iron recovery of 94.54%. In addition, more than 68.93% Al2O3 was recovered by leaching the slag, which was achieved by firstly roasted the slag at 900 °C for 2 h and then alkaline leaching at 95 °C for 2 h with a liquid-to-solid ratio of 10 mL/g. In addition, the alkaline leaching slag could potentially be used as raw material for construction purpose, which mainly consisted of SiO2 and CaO.

Recovery of an Acid Mine Drainage-Impacted Stream Treated by Steel Slag Leach Beds

The East Branch of Raccoon Creek, Ohio is highly impacted by pre-regulation coal mining and contains 10 steel slag leach beds that passively treat the low pH, and the Fe and Al-rich waters. Water chemistry, sediment chemistry, aquatic macroinvertebrate richness and diversity, habitat quality, and stream gradient were examined along the mainstem and a headwater tributary where multiple treatment systems are located. The stream gradient showed no significant relationship with sediment quality. Higher flows increased instream concentrations of Fe and the portion of suspended Fe in the water column. Macroinvertebrate richness and diversity varied from good to very poor and were negatively correlated with sediment Cu, Fe, Mn, and other water quality parameters such as specific conductivity and total dissolved solids, but were positively correlated with pH.

Ultrasound-Assisted Leaching and Kinetic Study of Blended Copper Slag

This article deals with the dissolution of blended copper slag (flash and converter furnace) in hydrogen peroxide and acetic acid in the presence of ultrasound. The parameters that are effective on leaching efficiency, such as leaching temperature, leaching time, ultrasound power, acetic acid concentration, and hydrogen peroxide concentration, were investigated. The optimum leaching conditions for maximum copper dissolution (93 pct) and minimum iron dissolution (3 pct) were determined as follows: 2 M H2O2, 4 M CH3COOH, 10 pct of ultrasound power, 65 °C of leaching temperature, 60 minutes of leaching time, and 1:25 of solid–liquid ratio. According to the Brunauer–Emmett–Teller (BET) analysis results on the original sample and leaching residue, the ultrasound caused formation of microcracks on the particle surface; however, the BET surface area increased and the mean adsorption pore width decreased. The apparent activation energy was found to be 55.35 kJ/mol, and the kinetics equations of the processes were established.

Preparation of highly pure vanadyl sulfate electrolyte from vanadium slag leach solution with the complexing effect of EDTA on Fe(III)

Direct acid leach solution of converter vanadium slag containing tetravalent vanadium is considered to be a low-cost raw material to produce highly pure vanadyl sulfate electrolyte for vanadium battery. The presence of Fe(III) in the primary stripped solution is an obstacle for the further purification process since a) it is hard to separate Fe(III) from V(IV) by solvent extraction b) it is difficult to completely reduce Fe(III) to Fe(II) in the presence of oxygen from the air. A series of complexing agents, i.e. ethylenediaminetetraacetic acid (EDTA), 5-sulfosalicylic acid (SSA) and citric acid were initiatively employed to complex the Fe(III) in the aqueous phase. The impact of Fe(III) complexation on the V(IV) extraction process by D2EHPA (Di-(2-ethylhexyl)phosphoric acid) were investigated and compared. The ligand number within each complex were calculated to instruct the complexant amount needed for complete Fe(III) complexation. Experimental results confirmed that EDTA is the preferred complexing agent compared to SSA and citric acid. >98% of Fe(III) in the aqueous phase can be complexed in a liquid phase by EDTA with a mole ratio of EDTA to Fe(III) of 1.5. Moreover, the complexation degree of Fe(III)-EDTA strongly depends on solution pH, and the maximum separation coefficient (βV/Fe = 729) between V(IV) and Fe(III) takes place at pH = 1.8 in the D2EHPA extraction system. A highly pure vanadyl sulfate electrolyte product can be obtained by two-stage extraction with the complexing function of EDTA.

Converter slag leaching in ammonia medium/column system with subsequent crystallisation with NaSH

Converter slags are by-products of pyrometallurgical processing of copper concentrates in Chile, which contain significant amounts of copper (close to 40.0% in the material considered here), converting them from a passive material (material that is not feasible to process) to an active material (it can be processed). This study analyses column leaching of converter slag with the use of ammonium hydroxide. A preliminary analysis was carried out on acid leaching (in an agitated system). Later, in ammonia medium, several variables were assessed, including particle size and NH4OH concentration, as well as different grades of acid purity to adjust the pH of the leaching solution. The experiments were carried out in 1.2 m high columns with a cross-section diameter of 7.5 × 10−2 m, using 2.0 kg of slag. The results show that using an acid system (i.e. ordinary leaching), reagent consumption reached 473.9 kg H2SO4/ton of slag, with copper recovery of only 50.8% and Fe recovery of over 67.0%. On the other hand, using an ammonia system, the recovery values reached 87.7% for Cu, with almost no impurities, with reagent consumption of 3.8 kg H2SO4/ton of slag. The working pH was 10.5. These recovery levels are due to the leaching of Cu2O and Cu° from the converter slag. When using an acid contaminated with impurities to adjust the pH, the copper extraction rate was increased. The impurities of antimony, bismuth and arsenic are not significant. The copper in pregnant solution (PLS) obtained was put into contact with NaSH to generate hydrated chalcanthite (CuSO4·5H2O) with a high grade of purity, while the remaining solution can be returned to the leaching stage due to its high level of ammonia content.

Constructed wetlands for steel slag leachate management: Partitioning of arsenic, chromium, and vanadium in waters, sediments, and plants

Constructed wetlands can treat highly alkaline leachate resulting from the weathering of steel slag before reuse (e.g. as aggregate) or during disposal in repositories and legacy sites. This study aimed to assess how metal(loid)s soluble at high pH, such as arsenic (As), chromium (Cr), and vanadium (V) are removed in constructed wetlands and how they accumulate in the sediments and the plants (Phragmites australis, common reed). The results show that reedbeds were very effective at removing calcium (98%), aluminium (81%), barium (98%), chromium (90%), gallium (80%), nickel (98%), and zinc (98%), and lowering pH and alkalinity. No statistical difference was found for As and V between leachate influent and wetland samples, showing that these metal(loid)s were not efficiently removed. As, Cr, and V were significantly higher in the reedbed sediments than in a reference site. However, sediment concentrations are not at levels that would pose a concern regarding reuse for agricultural purposes (average values of 39 ± 26 mg kg−1 for As, 108 ± 15 mg kg−1 for Cr, and 231 ± 34 mg kg−1 for V). Also, there is no significant uptake of metals by the aboveground portions of the reeds compared to reference conditions. Results show statistically significant enrichment in metal(loid)s in rhizomes and also a seasonal effect on the Cr concentrations. The data suggest minimal risk of oxyanion-forming element uptake and cycling in wetlands receiving alkaline steel slag.

Improving the Life Cycle Impact Assessment of Metal Ecotoxicity: Importance of Chromium Speciation, Water Chemistry, and Metal Release

Investigations of metal ecotoxicity in life cycle assessment (LCA) and life cycle impact assessment (LCIA) are becoming important tools for evaluating the environmental impact of a product or process. There is, however, improvement needed for LCIA of metal ecotoxicity in order to make this assessment more relevant and robust. In this work, three issues within the LCIA of metal ecotoxicity are investigated, mainly focusing on topics related to stainless steel manufacturing. The first issue is the importance of considering regional water chemistry when constructing the characterization factor (CF). A model freshwater of relevance for stainless steel manufacturing in a region of Sweden was created with chemistry different from available options. The second issue is related to the lack of consideration on changes in speciation of Cr(VI) in freshwater for a given emission, as Cr(VI) to some extent will be reduced to Cr(III). Two new options are suggested based on relationships between the Cr(VI)–total Cr ratio as a way to improve the relevancy of LCIA for Cr(VI) in freshwater. The last issue is how to treat metal release from slags in LCIA. Metal release from slags was shown to vary significantly between different ways of modelling slag emissions (differences in total metal content, slag leaching tests, estimated emissions to groundwater).