High quality steels have a low sulfur content. Steel is purified from sulfur by treating it with highly basic slags. Scarce fluorspar is used to provide slags with the required fluidity, which ...decomposes during smelting with the liberation of toxic fluorine into a workshop atmosphere. Alumina is also a thinner for highly basic slags, which is present in sufficient concentrations in aluminothermic production slags that are sent to landfill and create pressure on the environment. Slag dumps are “technogenic deposits” that can be a raw material base. In particular, industrial ferroalloy slags with a high alumina content may be used to prepare a thinning slag-forming mixture that can be used in steelmaking instead of scarce fluorspar. Preparation of a slag-forming mixture from waste slag will reduce the environmental pressure on slag dumps and their use as a slag thinner during steel refining in the working area of a steelmaking workshop by eliminating toxic fluorine emissions released during fluorspar decomposition. Replacement of scarce fluorspar with a slag-forming mixture in steelmaking will reduce steel cost by lowering aluminum consumption for slag deoxidation.
To describe the joint reduction of iron and copper from the oxide melt (1273–1773 K) of the B
2
O
3
–CaO–FeO–CuO system with carbon monoxide and hydrogen, we used thermodynamic modeling in the ...approximation to open systems, with fractional introduction of CO (H
2
) and periodic removal of metal phases and gases from the composition of the working fluid. The calculations are carried out taking into account the disproportionation of FeO into Fe and Fe
3
O
4
. For the considered compositions of the melt having a FeO/CuO ratio of 10, the disproportionation of the lower iron oxide and its interaction with CuO makes it possible to transform copper into the metallic state by 20–80% at low temperatures. The dependences of the contents of iron and copper oxides in the oxide melt, the degrees of their reduction, and the composition of the resulting alloy on the temperature and the amount of the introduced reducing agent are revealed. The required amount of hydrogen for the reduction of the metals to a fixed degree of copper metallization is shown to be significantly lower than that of carbon monoxide. The information obtained is useful for predicting thermoextraction processes occurring during the extraction of valuable components from nonferrous metallurgy slags.
—To describe the processes of fuming copper smelting slags by the products of methane conversion by oxygen at oxygen consumption coefficients (α) varying from 0.25 to 0.75 in the temperature range ...1473–1773 K, we have developed a thermodynamic modeling technique for open systems with fractional introduction of an initial reducing gas and periodic removal of a metallic phase and waste gases from a working medium. Relations between the contents of iron and zinc oxides in an oxide melt and the degrees of their reduction and the temperature and the amount of the introduced reducing agent are revealed. The thermodynamic equilibrium of a system is calculated on the assumption that solutions are ideal; that is, the activity coefficient of zinc oxide is 1. Under the real conditions of the slag melt of copper smelting,
a
ZnO
is close to 3. Therefore, the quantitative indicators of industrial smelting differ from the calculated ones. However, the change in the smelting parameters relative to each other would be the same. The main result of this work is a comparative analysis of the processes depending on the reducing gas temperature and composition. The amount of conversion products and, accordingly, natural gas required for their production, which is necessary for metal reduction to a given degree of zinc recovery, significantly depends on the gas temperature and composition. The data obtained are useful for predicting the thermal extraction processes that occur during the extraction of useful components from nonferrous metallurgy slags.
—The fuming of copper smelting slag in a Vanyukov furnace by the products of methane conversion by oxygen, water vapor, and carbon dioxide in the temperature range 1473–1773 K is thermodynamically ...modeled. For this purpose, a technique is developed to describe the changes in the phase compositions in the systems under study during their bubbling as functions of the amount of an introduced reducing gas; this technique is characterized by cyclic calculations and the removal of the formed gases and metal phase from the working medium composition. The calculation results demonstrate that the interaction of the gas with melt oxides proceeds in two stages regardless of the melt composition. At the first stage, Fe
3
O
4
is reduced to FeO and ZnO, to Zn. Therefore, the content of Fe
3
O
4
and ZnO in the melt decreases and that of FeO increases. At the second stage, metallic iron appears and the content of iron and zinc oxides decreases. A significant influence of temperature on fuming is shown. When the temperature increases from 1473 to 1773 K, the fuming process is significantly intensified, which is accompanied by a fourfold decrease in the amount of the reducing gas required to achieve close degrees of zinc recovery. The gas composition weakly affects the process. The most effective reducing agent is shown to be the gas formed by the steam conversion of methane, which is due to the minimal costs of its production. The results obtained make it possible to predict the indicators of the process of fuming by methane conversion products and will be useful for creating new technologies.
The paper presents the thermodynamic modeling results of zinc and iron reduction from B
2
O
3
–CaO–Fe
2
O
3
–ZnО melts by CO–CO
2
and H
2
–H
2
O mixtures containing 0–60% CO
2
(H
2
O) at 1273–1673 K ...using a technique describing the reduction of metals from an oxide melt by gas in bubbling processes, under conditions that provide an approximation to real systems. Its originality is equilibrium determination for each individual portion of gas supplied into the working fluid. The reducible metals oxides content in each calculation cycle is taken from the previous data. During the calculations, changes in the content of zinc (
С
ZnO
) and iron (
and
С
FeO
) oxides in the melt and the degree of their reduction were estimated. When using CO or H
2
as a reducing agent, this process proceeds in three stages. In the first stage, Fe
2
O
3
is reduced to Fe
3
O
4
and FeO.
values decrease to almost zero, while
and
C
FeO
increase simultaneously. By the end of the stage,
reaches its maximum value. At the second stage, the Fe
3
O
4
→ FeO transition occurs, when
С
FeO
values reach its maximum. At these stages, there is a slight increase in the
C
ZnO
. At the third stage, the values
C
FeO
and
C
ZnO
decrease, and iron and zinc are reduced. An increase in temperature dramatically reduces the gas consumption for zinc reduction by 2–3 times, and the replacement of CO with H
2
reduces it by less than 20%. In the presence of oxidizing agents (CO or H
2
O), only zinc is reduced. The process ends when the final content of zinc oxide in the melt corresponds to the equilibrium with the initial gas composition. The higher the temperature, the less
C
ZnO
is. The obtained data are useful for the development of technologies for the selective recovery of metals.
To predict the conditions for metals reduction from an oxide melt by gas in bubbling processes, a thermodynamic modeling technique has been developed that provides an approximation to real systems. ...The main difference between the accepted method and the well-known one is in conducting successive calculation cycles with withdrawal of the generated gases and the metal phase from the working medium. This paper presents the results of thermodynamic modeling of nickel and iron reduction processes from B
2
O
3
–CaO–Fe
2
O
3
–NiO melts by mixtures of CO–CO
2
and H
2
–H
2
O containing 0–60% CO
2
(H
2
O) in the temperature range of 1273–1673 K. The calculations evaluated the content of nickel and iron oxides in the melt and the degree of their reduction. It is shown that, regardless of the gas composition, this process proceeds in several stages. At the first stage, Fe
2
O
3
is reduced to Fe
3
O
4
and FeO.
values decrease to almost zero, while
and
C
FeO
increase simultaneously. By the end of the phase,
reaches its maximum value. At the second stage, the Fe
3
O
4
→ FeO transition occurs, when
С
FeO
values reach maximum, nickel and iron begin to reduce to metal. At reduction by CO–CO
2
mixture, an increase in temperature reduces the metallization of both nickel and iron. Similarly, an increase in the CO
2
content of the introduced gas affects. During interaction of the oxide melt with a gas containing 60% CO
2
, the third stage is absent. At reduction by H
2
–H
2
O mixture, an increase in temperature reduces the metallization of nickel, but increases metallization of iron. With increasing water vapor content in the introduced gas, the degree of metallization of both nickel and iron decreases. The obtained data are useful for creating technologies for selective reduction of metals and formation of ferronickel of the required composition.
Ferronickel, currently obtained from oxidized nickel ores in various aggregates, contains from 5 to 20% of Ni. According to experiments, rich ferronickel (with a content of Ni of about 70%) can be ...obtained from the melt of silicate-nickel ore treated with reducing gas. The thermodynamic modeling of metallurgical processes, adapted to open systems, is used to consider the features of reducing the high-iron nickel ore from the Serovskoye deposit with carbon monoxide. The oxide melt composition used for the calculations includes 60.4 wt % of Fe
2
O
3
, 1.4 wt % of NiO, 0.14 wt % of СоО, 5.8 wt % of А1
2
O
3,
17 wt % of SiO
2
, 4.2 wt % of MgO, and 11.1 wt % of CaO. The simulation was carried out at a pressure of 0.1 MPa, an amount of carbon monoxide of 10.6 dm
3
/kg per portion, and temperatures of 1673, 1723, 1773 K. During calculations, dependencies are found that connect the content of nickel (
C
NiO
), iron (
C
FeO
) and cobalt (
С
СoО
) oxides in the oxide melt and metals in the alloy (
С
Ni
,
С
Fe
,
С
C
o
), as well as their transition degree from the metallic state (φ
Ni
, φ
Fe
, φ
Co
) to the amount of introduced gas. The component contents in one portion of reduced metal are determined. At temperatures of 1673 to 1773 K and an introduced amount of CO of 190 dm
3
/kg, the respective content of Fe
2
O
3
, Fe
3
O
4
, FeO, NiO, and CoO in the oxide melt is 0.17 to 0.12%, 1.77 to 1.05%, 55.6 to 56.5%, 0.026 to 0.037%, and 0.061 to 0.068%. At a nickel reduction degree of 98%, the respective degrees of iron and cobalt reduction are 5 and 56 to 61%. An alloy formed from the reduced metals contains about 30% of Ni, 63 to 65% of Fe and 2% of Co. Thus, it is shown that the selective reduction of nickel and cobalt is possible in certain conditions. The findings from the study are significant to validating the parameters of the production process of ferronickel from oxidized high-iron nickel ores.
The technological process of steel smelting at “ArcelorMittal Temirtau” JSC includes three stages: converter smelting of semi-finished products, ladle treatment, and continuous casting of slabs. ...According to the current technology, a desired flowability of the refining slag is created in the ladle-furnace unit by thinner additives, such as fluorspar. When using fluorspar, toxic fluorine emissions aggravate the environmental situation at the worksite. In addition, the presence of fluoride compounds in the slag adversely affects the durability of the ladle lining. Without modifying the technological process and the consumption of slag-forming agents (lime), solid slag mixtures, based on aluminum oxide, can be used in the ladle-furnace unit to eliminate fluorine emissions into the workshop atmosphere, neutralize the negative effect on the resistance of the ladle lining slag belt, as well as reduce the cost of steel due to the refusal of fluorspar and reduced consumption of aluminum for slag deoxidization.
The coreduction of iron and zinc from the B
2
O
3
–CaO–FeO–ZnO oxide melt by carbon monoxide or hydrogen is described by means of thermodynamic simulation in approximation to real processes; it ...provides batch addition of a reducing gas and removal of a metallic phase and waste gases. The calculations are carried out with allowance for the disproportionation of FeO into Fe and Fe
3
O
4
. For a mass ratio FeO/ZnO = 10, the disproportionation of FeO ensures the transition of 1.3–1.5 wt % Zn into gas. Upon addition of hydrogen or carbon monoxide to the system, the oxide melt composition is modified: the fractions of iron and zinc oxides decrease, but the degree of their metallization (φ
Fe
, φ
Zn
) increases. Complete (>99%) transition of zinc into a gas phase at 1773 K and 1673 K is detected upon addition of hydrogen in an amount of 36 and 65 dm
3
/kg, respectively, or of carbon monoxide in an amount of 58 and 80 dm
3
/kg, respectively. When hydrogen is used, the degree of iron metallization reaches 24.0–15.8% in the temperature range 1337–1573 K against 11.0–6.0% for carbon monoxide. The temperature increment in the considered
V
CO
and
flow rate ranges decreases the degree of metallization φ
Fe
. The obtained data can be used to adjust the conditions of treatment of oxide (slag) melts and to achieve the required degrees of metallization of zinc and iron.
