It looks as if it was frozen lava, but it is a by-product of metal smelting. If left piled up, it may have a strong negative impact on the environment. But when reused in a smart way, it can actually bring many benefits.
This article contains information concerning of the analysis the possibility of defining refinery qualities of the slag based thermophysical and thermodynamical data. The paper presents a model of slag refining processes and a method of determining the reduction capability of slag solutions. Slag was analysed with the use of the DTA methods for the brass melting conductions. The study of computer program including the satisfactory number of data there are used in to the design a modern device rotating head used for gas-slag refining. It was achieved that the refining gas and fluxes were distributed ever by the rotating head. High effectiveness of the gas-slag refining processes was proved for the brass.
Among the elements that compose steel slags and blast furnace slags, metallic precipitates occur alongside the dominant glass and crystalline phases. Their main component is metallic iron, the content of which varies from about 90% to 99% in steel slags, while in blast furnace slags the presence of precipitates was identified with the proportion of metallic iron amounting to 100%. During observations using scanning electron microscopy and X-ray spectral microanalysis it has been found that the form of occurrence of metallic precipitates is varied. There were fine drops of metal among them, surrounded by glass, larger, single precipitates in a regular, spherical shape, and metallic aggregates filling the open spaces between the crystalline phases. Tests carried out for: slags resulting from the open-hearth process, slags that are a by-product of smelting in electric arc furnaces, blast furnace slags and waste resulting from the production of ductile cast iron showed that depending on the type of slag, the proportion and form of metallic precipitates is variable and the amount of Fe in the precipitates is also varied. Research shows that in terms of quality, steel and blast furnace slag can be a potential source of iron recovery. However, further quantitative analyses are required regarding the percentage of precipitates in the composition of slags in order to determine the viability of iron recovery. This paper is the first part of a series of publications aimed at understanding the functional properties of steel and blast furnace slags in the aspect of their destructive impact on the components of devices involved in the process of their processing, which is a significant operational problem.
Research of metallurgical slags chemical composition, originating both from current production as well as gathered in dumping grounds formany years, show that they are very diversified. Slags contain substantial amounts of metals, including heavy metals, apart from elements from groups of non-metals and lanthanoids. In the article occurrence forms and relations with phase components of selected metals (iron, manganese, zinc, lead and others) on the basis of mineralogical and chemical research on slags after steel and ore Zn-Pb production were characterized. It was stated that metals may occur in metallurgical slags as fine drops not separated from slag during a metallurgical process, may form polymetallic aggregates, their own phases (especially oxide ones) and hide in structures of silicate phases. A considerable amount of metals is dissipated in glaze and amorphous substance. The conducted research delivers information on the occurrence of metals in metallurgical slags, which is extremely important during work connected with economic exploitation of slags. It especially refers to increasing attempts of acquiring elements from metallurgical slags. These activities determine the necessity of analyzing chemical and phase composition of slags because they may be an important indication, for instance while working on a proper technology of elements recovery.
A special Slag-Prop Cu database has been developed to archive data from laboratory and industrial tests related to post-reduction slags. In
order to enrich the data areas, it was decided to design a system for measuring the temperature of the liquid slag and its viscosity. Objectives
of research work are to gather information on the properties of post-slags such as the temperature of liquid slag and its viscosity. The
discussed issues are especially important in the foundry practice. Designed research stand and using of database applications can greatly
facilitate the work of metallurgists, foundrymen, technologists and scientists. The viscosity measurement was developed and presented
earlier. The author's analytical methodology was supplemented by a thyristor measuring system (described in the article). The system
temperature measurement can be performed simultaneously in 3 ways to reduce the measurement error. Measurement of the voltage mV -
using the Seebeck effect can be measured throughout the entire range of thermocouple resistance, up to 1300 °C. Direct temperature
measurement ⁰C - measurement only below 1000 ⁰C. Additional measurement - the measurement can also be read from the pyrometer set
above the bath. The temperature and the reading frequency depend on the device itself. The principle of measurement is that in a molten
metal / slag crucible, we put a N-type thermocouple. The thermocouples are hung by means of a tripod above the crucible and placed in a
crucible. The thermocouple is connected to a compensating line dedicated to this type of thermocouple. The cable is in turn connected to a
special multimeter that has the ability to connect to a computer and upload results. Temperature measurement can be performed
simultaneously in 3 ways to reduce the measurement error. The Sn-Pb alloy has been subjected to testing for proper operation of the device.
In this foot should be observed the supercooling of the liquid, which initiates the crystallization process and in which latent heat begins to
exude raising the temperature until the coagulation temperature is reached.
The post-processing slags containing about 0.8 wt.% of copper were subjected to the treatment of a complex reagent. The chemical composition of the complex reagent has been elaborated and patented in frame of the Grant No. PBS3/A5/45/2015. The slags had an industrial origin and were delivered by the Smelter and Refinery Plant, Głogów, as a product of the direct-to-blister technology performed in the flash furnace assisted by the arc furnace. An agglomeration of copper droplets suspended in the liquid slag, their coagulation, and deposition on the bottom of furnace were observed after the treatment this post-processing slag by the mentioned reagent. The treatment of the post-processing slags by the complex reagent was performed in the arc furnace equipped with some additional electrodes situated at the furnace bottom (additional, in comparison with the arc furnace usually applied in the Smelter and Refinery Plant, Głogów). The behaviour of the copper droplets in the liquid slag within the competition between buoyancy force and gravity was studied from the viewpoint of the required deposition of coagulated copper droplets. The applied complex reagent improves sufficiently the surface free energy of the copper droplets. In the result, the mechanical equilibrium between coagulated copper droplets and surrounding liquid slag is properly modified. Eventually, sufficiently large copper droplets are subjected to a settlement on the furnace bottom according to the requirements. The agglomeration and coagulation of the copper droplets were significantly improved by an optimized tilting of the upper electrodes and even by their rotation. Moreover, the settlement was substantially facilitated and improved by the employment of both upper and lower system of electrodes with the simultaneous substitution of the variable current by the direct current.
Metallurgical slag is often treated as a material which could be used in the waste management, especially for production different kinds of aggregate. So it is necessary to know that material not only considering technical properties, but also its mineral and chemical composition. Such researches could deliver many valuable information during the waste utilization. Researches were made for samples of the metallurgical slag after steel and Zn-Pb production. Samples were taken from chosen dumps localized in the Upper Silesian District. Beside metallic aggregates, silicate and oxide phases, glaze is one of the main component of the metallurgical slag. The following stages of the glaze devitrification were presented; from not transformed and isotropic glaze pieces to the strong weathered glaze. Transformed glaze is red or brown with the cracks on the surface. Cracks are often filled by the metals oxides, which can be liberated during the glaze devitrification. On the base of researches executed using the electron microprobe the chemical glaze composition was presented. The chemical composition of the glaze is variable what is connected with the kind of the metallurgical slag. The following main elements were distinguished in the metallurgical slag: Si, Al, Fe, Ca and Mg. Slag after steel production contains also Mn, P, S and the slag after Zn-Pb production contains: As, Cd, Cu, Mn, Ni, Pb, Ti, Zn, Na, K, P and S.
Copper slag differs by chemical composition and structure, depending on the type of processing. Copper slag typically contains about 1 wt.% copper and 40 wt.% iron depending upon the initial ore quality and type of furnace used. The aim is to produce a typical foundry pig iron with the chemical composition of C > 3.40 wt.%, Si 1.40 to 1.80 wt.%, Mn 0.30 to 0.90 wt.%, P < 0.03 wt.% and S < 0.03 wt.% from copper slag. But foundry pig iron manufactured from copper slag contains a high sulphur content. Therefore, this study examines how to conduct desulphurization. Desulphurization roasting and reduction smelting with desulphurization additives used to remove sulphur from the copper slag. The results showed that desulphurization effect of desulphurization roasting is poor but when combined with reduction smelting with CaO addition is possible to manufacture low sulphur pig iron from copper smelting slag.
The physical and chemical properties of cements with slag originated from the storage yards of different age, added as a supplementary cementing material are highlighted. The materials after 20-year storage, the crushed slag after approximately 2-year storage and the new slag from the ongoing production were compared. The materials supplied by the same metallurgical plant were characterized. The blended cements were produced by Portland cement clinker grinding with gypsum and slags added as 5 to 50% of binder mass. The standard properties of cements were examined, as well as some experiments related to the kinetics of hydration and hydration products were carried out. The addition of granulated blast furnace slag (GBFS) stored for a long time, as a component of cement, affects the properties of material in such a way that the early compressive strength is not specially altered but at longer maturing the strength decreases generally with the storage time and percentage of additive. This is related to the reduction of the vitreous component, as well as to the presence of weathered material of altered activity. At the additive content up to 50% the binder complying with the requirements of the European standards for CEM III/A or CEM II/(A,B)-S common cements can be produced. The cements with the old slag meet the requirements of EN 197-1 relating at least to the class 32,5. The role of calcium carbonate, being the product resulting from the slag weathering process, acting as a grindability and setting/hardening modifying agent, should be underlined.
Evaluating soil strength by geophysical methods using P-waves was undertaken in this study to assess the effects of changed binder ratios on stabilization and compression characteristics. The materials included dredged sediments collected in the seabed of Timrå region, north Sweden. The Portland cement (Basement CEM II/A-V, SS EN 197-1) and ground granulated blast furnace slag (GGBFS) were used as stabilizers. The experiments were performed on behalf of the Svenska Cellulosa Aktiebolaget (SCA) Biorefinery Östrand AB pulp mill. Quantity of binder included 150, 120 and 100 kg. The properties of soil were evaluated after 28, 42, 43, 70, 71 and 85 days of curing using applied geophysical methods of measuring the travel time of primary wave propagation. The P-waves were determined to evaluate the strength of stabilized soils. The results demonstrated variation of P-waves velocity depending on stabilizing agent and curing time in various ratios: Low water/High binder (LW/HB), High water/Low binder (HW/LB) and percentage of agents (CEM II/A-V/GGBFS) as 30%/70%, 50%/50% and 70%/30%. The compression characteristics of soils were assessed using uniaxial compressive strength (UCS). The P-wave velocities were higher for samples stabilized with LW/HB compared to those with HW/LB. The primary wave propagation increased over curing time for all stabilized mixes along with the increased UCS, which proves a tight correlation with the increased strength of soil solidified by the agents. Increased water ratio gives a lower strength by maintained amount of binder and vice versa.
Nickel slag has a high-content iron and is a secondary utilization resource with great development potential. The coal-based direct reduction is an innovative technology that can be used to utilize the iron resources in nickel slag. The effect of the particle size of nickel slag on the strength and the reduction of nickel slag-coal composite briquettes were investigated. Four samples with particle size of 75~106 μm, 106~150 μm, 150~270 μm, and >270 μm were selected. The drop strength increased 9.4 times and the compressive strength reached 281.1 N when the nickel slag particle size decreased from >270 μm to 75~106 μm. The reduction degree determined by the data from the thermogravimetric experiment indicated that its maximum was 79.545%. The reduction experiments performed at 1200°C for 45 minutes indicated that the nickel slag with particle sizes between 75~106 µm were appropriate for the reduction of the nickel slag-coal composite briquettes.