Ferrochrome Slag Research Articles

English

Ferrochrome slag generated from alumino-thermi method piles up in large quantities poses many problems to the environment and contaminates ground water on long run, needs to be addressed very urgently. It principally contains chromium, alumina, Iron, magnesium, calcium in small quantities. This paper deals with extraction of chromium and renders the slag harmless. In this paper industrial waste was collected from GTS industries and used in the subsequent experimentation. Ferrochrome slag is treated with lime to conduct slag-lime solid-solid reaction. Chromium present in the slag reacts with lime to form mixed chromates. The reaction is conducted at 973K, soluble chromium ion was extracted with water and is subsequently separated by adsorbing fly ash based zeolite which can be recovered. The recovery of chromium metal in the slag is 64%. The method is viable for the commercial recovery of chromium from slag.

Magnetic separation and extraction chrome from high carbon ferrochrome slag

High carbon ferrochrome slag (HCFS) is a byproduct from the production of ferrochrome, and there is no effective method to deal with it. In this paper, aiming at comprehensive utilization of HCFS, magnetic separation is determined to separate and extract chromium materials from HCFS. The investigation and characterization show that most of the chromium exists in magnetic materials such as iron chromium spinel and ferrochrome in HCFS. The factors which affect significantly the magnetic separation are investigated. It is indicated that the content of the chromium in the concentrate is increased along with increasing of the magnetic field intensity, while on the contrary, smaller particle size is benefited to obtain the higher chrome percentage concentrate. The optimal magnetic separation condition is achieved as follows, when the current reaches 2.4 A and the particle size is above 150 μm, the percentage of chromium extracted from HCFS is the maximum as 24.9%.

USE OF LOCAL NATURAL SILICEOUS RAW MATERIAL AND WASTES FOR PRODUCTION OF HEAT-INSULATING FOAMCONCRETE

The article analyzes the resource base, reserves and the use of siliceous rocks, their economic feasibility of the use for production of building materials of new generation with low-energy and other costs. Presented are the results of laboratory research and testing technology of production of insulating foam from a composition based on an aqueous solution of sodium silicate obtained from the local siliceous rocks (diatomite) and the liquid alkali component - soapstock, hardener from ferrochrome slag and waste carbonate rock able to harden at a low temperature processing ( 100-110 ° C).

Implementation of industrial waste ferrochrome slag in conventional and low cement castables: Effect of calcined alumina

A new class of conventional and low-cement ferrochrome slag-based castables were prepared from 40 wt.% ferrochrome slag and 45 wt.% calcined bauxite. Rest fraction varied between high alumina cement (HAC) acting as hydraulic binder and calcined alumina as pore filling additive. Standard ASTM size briquettes were prepared for crushing and bending strengths evaluation, and the samples were then subjected to firing at 800, 1100 and 1300 °C for a soaking period of 3 h. The microstructure and refractory properties of the prepared castables have been investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM), cold crushing strength, modulus of rupture and permanent linear changes (PLCs) test. Castables show good volume stability (linear change <0.7%) at 1300 °C. The outcomes of these investigations were efficacious and in accordance with previously reported data of similar compositions. High thermo-mechanical and physico-chemical properties were attained pointing out an outstanding potential to increase the refractory lining working life of non-recovery coke oven and reheating furnaces.

Heat-resistant ferrochrome slag based concrete

Heat-resistant ferrochrome slag based concrete

Mechanical properties and setting time of ferrochrome slag based geopolymer paste and mortar

Many researches have been done to investigate using raw materials in the production of geopolymer cements. This paper presents the effects of alkali dosage and silica modulus when using sodium metasilicate solution at different curing conditions on the geopolymerization of ferrochrome slag (FS). As alkali activation for geopolymerization, NaOH and Na2SiO3 solution were used. Geopolymer cement was produced using FS as raw material with 3 different silica modulus (0.50, 0.60 and 0.70) and 4 different Na2O concentrations (4%, 7%, 10% and 12%). The setting time, hydration heat and compressive strength of geopolymer paste samples and compressive strength of geopolymer mortar samples were obtained. The setting time varied between 120 and 870min, it showed variability depending on Na2O content. The highest 28day compressive strength of the geopolymer paste samples was obtained from one with Na2O concentration of 7% and silica modulus of 0.70. Geopolymer mortars were prepared for the determination of compressive strength by adding FS:sand:alkali activator ratio 1:2:0.30, 0.35 and 0.40. The specimens were cured at 60°C and 80°C kept for 20h and the other mortar samples were stored under laboratory conditions. Compressive strength of the material decreased, when w/b (water/binder) ratio increased. The highest 28day strength of the geopolymer mortar was obtained at 0.30w/b ratio and laboratory temperature curing conditions. The hydration heat of geopolymer paste samples was found to be less than normal Portland cements. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) were investigated to study the microstructural properties of the geopolymers.

Implementation of industrial waste ferrochrome slag in conventional and low cement castables: Effect of microsilica addition

Ferrochrome slag is a waste material obtained from the manufacturing of high carbon ferrochromium alloy. This slag is formed as a liquid at 1700 °C and its main components are SiO2, Al2O3 and MgO. Additionally it consists of chrome, ferrous/ferric oxides and CaO. Present work outlines a novel approach in formulating castables with this industrial waste.

Neutron Radiation Tests about FeCr Slag and Natural Zeolite Loaded Brick Samples

Neutron shielding performances of new brick samples are investigated. Brick samples including 10, 20, and 30 percentages of ferrochromium slag (FeCr waste) and natural zeolite are prepared and mechanical properties are obtained. Total macroscopic cross sections are calculated by using results of 4.5 MeV neutron transmission experiments. As a result, neutron shielding capacity of brick samples increases with increasing FeCr slag and natural zeolite percentages. This information could be useful in the area of neutron shielding.

Environmental and technical assessment of ferrochrome slag as concrete aggregate material

Ferrochrome slag is a major solid waste generated from submerged electric arc furnaces during manufacturing of ferrochrome alloy. The waste slag has excellent mechanical and engineering properties for utilization as concrete aggregate material. But it contains about 6–12% of residual chromium which has the potentiality of releasing hazardous chromium compounds to the environment. This research work carried out the mineralogical and chemical characterization study to find out the major chemical elements and mineral phases in the solid slag matrix. Physico-mechanical experimental studies indicated the suitability of the slag as aggregate material in concrete work. The concrete product with ferrochrome slag as coarse and fine aggregate showed excellent results with respect to compressive strength and were found to be suitable for general purpose concrete work. The standard leaching experimental results showed that the leachable chromium remains well immobilized in the cement and concrete matrix with very low to non-detectable level of chromium leaching. The results indicated the technical acceptability and the environmental compatibility of the slag as concrete aggregate material.

A Statistical Approach for Estimation of Fusion Behavior of Alumino-Thermic Ferrochrome Slags

Effects of simultaneous variations of Al2O3/CaO ratio, and MgO and CaF2 contents, on the fusion behavior of synthetic alumino-thermic ferrochrome slags are systematically measured using a hot-stage-microscope in accordance with German standard 51730. Empirical equations are developed for the prediction of the softening temperature (ST), liquidus/hemispherical temperature (HT), and flow temperature (FT), in terms of aforementioned variables using Factorial Design Technique. To verify the predicted equations, further groups of synthetic slags are prepared in the laboratory using pure oxides, and the characteristic temperatures of these slags are measured in the same manner using hot-stage microscope. It is observed that within the range of variables examined, equations developed render the best fit for HT, the next best fit for FT, and somewhat good fit for ST.

Properties of bricks with waste ferrochromium slag and zeolite

Effect of ferrochromium slag, zeolite and combinations on physical, mechanical, thermal conductivity and microstructure properties of bricks was investigated. They were substituted to brick raw material. Semi-dry mixtures were compressed with 20 MPa. Samples were fired at rate of 5 °C/min until 900 °C for 2 h. Characterization of fired bricks, density, porosity, water absorption, weight loss, compressive and bending strength, thermal conductivity properties and microstructural and phase analysis of bricks were determined. Mechanical strengths of bricks were higher than 7 MPa. Thermal conductivity of samples decreases 42.3%. Results showed that bricks with zeolite and slag could be used as construction material.

X-Ray, Gamma, and Neutron Radiation Tests on Epoxy-Ferrochromium Slag Composites by Experiments and Monte Carlo Simulations

Radiation shielding effects of ferrochromium slag loading hardened epoxy resin samples were investigated. Five different samples including different percentages of epoxy resin and ferrochromium slag were produced. X-ray, gamma ray, and neutron particle transmission experiments were performed for epoxy-ferrochromium slag composites. Also, FLUKA Monte Carlo simulations were made to obtain absorbed doses. As a result, radiation shielding performance increases with increasing ferrochromium slag additive in epoxy.

Water-Soluble Cr (VI) of Solidification-Cured Process and Compressive Strength of Ferrochrome Slag Complex Cement

Ferrochrome slag, an essential component in stainless steel, is the by-product of ferrochromium production. The composition of the ferrochrome slag and leaching tests show that the chromium content, 3.68%, is high, although the data of leaching tests under normal conditions is very low. Leaching test was performed on an oscillating shaking table with ratio adjusted to 150r/min at L/S 8 and 80°C, during 5h. The maximum content of water-soluble Cr (Ⅵ) is 2.78μg/g (0.3475 mg/L) from ferrochromium slag under these conditions. The soluble (Cr6+ and Cr3+) content rise in the solidification process，with the increase of ferrochrome slag. The Water-soluble Cr (Cr6+ and Cr3+) under different cured times can’t be detected. The content of ferrochrome slag reached 10% is the best ratio by comprehensive consideration of water-soluble Cr (Ⅵ) of all processes, compressive strength and relevant national standards.

Release behaviour of chromium from ferrochrome slag

Huge amount of ferrochrome slag, a solid waste is being generated from submerged electric arc furnace during manufacturing of ferrochrome alloy. The waste slag contains about 6–12% chromium as chromium oxide and it has the potentiality of releasing hazardous chromium compounds. Although chromium exists in the slag as highly immobile Cr (III) state, there is possibility of chromium release under different adverse conditions inter alia its conversion to highly leachable Cr (VI) state. While Cr (III) is an essential trace element in glucose synthesis, the Cr (VI) compounds are very toxic and highly leachable. This leaching characteristic may classify the slag as hazardous waste and restricts its use and disposal. Release of chromium from granulated slag was evaluated under laboratory batch studies with varying different experimental conditions. The results were analysed to find the conditions for maximum release of total chromium from the slag.

Use of Ferrochromium Slag as an Artificial Aggregate in Pavement Layers

Abstract This paper reports the results of experiments aiming to identify the properties of ferrochromium slag when it is used as an artificial aggregate for preparation of granular layers of flexible pavements. The experimental program consisted of three stages: (1) study of the physical and chemical properties of slag, (2) leaching of heavy elements of slag in terms of environmental impact, (3) study of the mechanical properties of specimens made with ferrochromium slag and limestone as aggregate. In the laboratory, cylindrically prepared specimens were tested in a repeated load triaxial (RLT) test apparatus. In addition, particle size analysis, abrasion, frost resistance, compaction, CA bearing ratio, and leaching tests were performed on the materials prior to RLT testing. The results indicate that the physical and mechanical properties of air-cooled ferrochromium slag are as good as those of natural aggregates. It can be used as a base or sub-base material in highway pavements and as an embankment material. Furthermore, the use of the slag as aggregate in pavement layers reduces the requirement for natural aggregates and saves the existing natural resources.

Catalytic activity of ferroalloy slags

869 Slags obtained in ferrous metallurgy may poten� tially be used as catalysts in the deep oxidation of poly� cyclic aromatic hydrocarbons from metallurgical pro� duction (1). Accordingly, it is of interest to study the catalytic properties of ferroalloy slags. In the present work, we investigate the catalytic properties of ferroalloy slags in the deep oxidation of polycyclic aromatic hydrocarbons. The output of ferroalloy slags in the Common� wealth of Independent States is more than 5 million t/yr. Slags obtained in the production of ferrochrome alloys differ in chemical and mineralogical composi� tion and in physicochemical properties. The following ferrochrome slags are formed: regular carbon slags, lowcarbon and carbonfree refining slags, and mod� eratecarbon converter slags (2, 3). Structurally, the slags consist of highrefractory spinels, forsterite, and glass saturated with spinel inclusions. The slags con� tain 2-4% chromospinelide (Mg, Fe)O ⋅ (Cr, Al)2O3; 10-15% spinel MgO ⋅ Al2O3; 15-20% forsterite 2MgO ⋅ Si 2 O 3 ; 50-55% glass; up to 1% metallic beads (Cr, Fe); and 0.7-1.0% sulfide phase FeS-CrS. The slags from silicochrome production contain a small quantity (0.3-0.5%) of chromium oxides; its basic components are oxides of silicon, aluminum, and cal� cium. Analysis of the chemical composition and physico� chemical properties of ferroalloy slags suggests that converter slags from the production of moderateand lowcarbon ferrochrome are the best for the catalysis of deep oxidation. Such slags contain the greatest quantity of catalytically active oxides: up to 70% chro� mium oxides and 2% iron oxides. In the present work, we investigate moderatecarbon ferrochrome slag from Aktyubinsk ferroalloy plant. In smelting manganese alloys, slag that is rich in manganese oxide (14.0-52.5%) is formed, as we see in the table (2, 4). Slag from the production of lowphos� phorus manganese corresponds to Technical Specifi� cations TU 14�11�85-73, and contains at least 65% manganese. Manganese slag is formed from the reduc� tion products of higher manganese oxides and fluxing additives (quartzite). The basic components of this slag are manganese oxide MnO (up to 60%), silica SiO 2 (up to 30%), alumina Al2O3 (up to 3%), calcium oxide CaO (up to 4%), and magnesium oxide MgO (up to 3%). Up to 3% K2O and Na2O are present. The melting point of the slag is around 1208°C. In smelting silicomanganese, slag containing 14-17% MnO is formed. The slag mainly consists of silicate of close� packed manganese-calciumsilicate glass of busta� mite type (CaO ⋅ MnO ⋅ 2SiO2); metal beads are present. The slag from the production of carbon and moderatecarbon ferromanganese consists mainly of oxides of manganese (40-50%), silicon (25-35%), alu� minum (0.9-3.0%), and calcium (7-23%). In mineral� ogical composition, the slags consist mainly of tephroite (2MnO ⋅ SiO 2 ) and forsterite (2MgO ⋅ SiO 2 ), with small quantities of bustamite (CaO ⋅ MnO ⋅ 2SiO 2 ). Analysis of the chemical and mineralogical com� position indicates that all the manganese slags consid� ered contain catalytically active oxides; their content is greatest in lowphosphorus manganese slag. All the slags are tested in deep catalytic oxidation.

Mechanical properties of ferrochromium slag in granular layers of flexible pavements

Ferrochromium slag is a waste material obtained from the manufacture of ferrochromium (FeCr). This article reports the results of experiments, aiming to identify the properties of ferrochromium slag when it is used as an artificial aggregate for preparation of granular layers of flexible pavements. The experimental program consisted of two stages: (1) study of the physical and chemical properties of slag; (2) study of the mechanical properties of specimens made with ferrochromium slag and limestone as aggregate. Laboratory prepared cylindrical specimens were tested in repeated load triaxial (RLT) test apparatus, developed at Suleyman Demirel University, Turkey. In addition, particle size analysis, abrasion test, frost resistance, compaction test, California Bearing Ratio (CBR) test and leaching test were performed on the materials prior to RLT testing. The results indicate that the physical and mechanical properties of air-cooled ferrochromium slag are as good or better than those of natural aggregates. Therefore, FeCr slag and SiFeCr slag have potential to be used as a pavement base layer material in applications where crushed limestone aggregate materials are traditionally used.

FERROKROM CÜRUFUNUN YOL TEMEL MALZEMESİ OLARAK KULLANIMI

Use of Ferrochromium Slag as Highway Base Material This study deals with the research of the use of the Ferrochromium slag (Electric-Arc furnace slag) in base layer material of road pavements. These materials were examined whether they are used for flexible pavement base layer aggregates instead of natural aggregates (limestone) or not. In this study, laboratory tests were carried out on the prepared specimens to represent the base course layers. CBR and Proctor tests were carried out on unbounded granular material mixtures and unconfined compression test were carried out on bounded mixtures. Consequently, it is concluded that Ferrochrome slag is used for granular layers of road pavements instead of natural aggregates in point of its physical and mechanical characteristics and slag mixtures stabilized with cement constitute a good alternative to

Green Container Glass Based on Ferrochromium Industrial Slag

The possibility of using ferrochromium slag added into the material in the amount of more than 6% (up to 20%) is considered. The physicochemical properties of synthesized samples are investigated, their working parameters (temperature interval of forming, relative speed of the machine, crystallization index) are identified. The glass of this composition satisfies all requirements imposed on its working properties and can be recommended for the production of green glass bottles.

Hexavalent chromium removal by ferrochromium slag

The aim of this study is to demonstrate the potential of Cr(VI) generation during jigging operation applied for ferrochrome recovery from slag. The Cr(VI) concentration s of water contacted with ferrochromium slag (W/FS = 10) in a closed cycle after 50 batches were found as 0.61 mg/l. Also, reduction of Cr(VI) to Cr(III) and a subsequent precipitation of Cr(III) by using ferrochrome slag (FS) in a model solution has been aimed. The effects of amount of acid, contact time, FS dosage, initial Cr(VI) concentration and temperature on the Cr(VI) reduction have been studied through the batch runs. The amount of acid has been found to be the most effective parameter affecting the Cr(VI) reduction. A 10 g/l FS dosage and 3.5 ml/l H 2SO 4 (5 M) are sufficient to reduce all Cr(VI) in the model solution containing 10 mg/l Cr(VI) and for contact time of 60 min at 25 °C. In reduced solutions, precipitation of metal ions has been studied by using extra FS. A 60 g/l dosage of fresh FS can precipitate all Cr(III) and Fe ions in the reduced solution. Thus, it has been demonstrated that the treatment of jigging water stream to be generated in a ferrochrome plant containing Cr(VI) can be accomplished by using ferrochromium slag and sulphuric acid. Also, it has been determined that solid residues of the process are environmentally stable by applying TCLP test.