大规模生产FRHC铜和阳极铜的成本优化

废杂铜是一种有价资源,它应用于精矿铜冶炼、再生铜和铜加工行业。根据废杂铜质量,可以直接用它生产不同类型的半成品,如:阳极铜、铜棒或作为精矿铜冶炼过程中的冷却材料。尤其是高品质的废杂铜可用作倾斜式和固定式反射炉的炉料,后者广泛用于回收废杂铜。这种炉子采用单一物料进行熔炼、精炼和浇铸生产阳极铜,或是生产用于制作铜棒的FRHC铜(火法精炼高导电性铜)。精矿铜冶炼的特点是冶炼厂的年生产能力越来越高,单位生产成本越来越低。对比精矿铜冶炼的最新发展,FRHC铜棒和新的再生铜厂的生产中看不到这种趋势。然而,单位生产成本低对于废杂铜的回收极为重要,因为要比精矿冶炼厂生产阴极铜拥有成本优势。大部分用于生产FRHC铜棒的炉子年生产能力仍然很小,每天的生产能力仅为50～80t。本文提出为什么再生铜行业尤其是生产FRHC铜棒的炉子没有明显大型化的趋势。不同炉型的单位生产成本和单位投资成本之间的差异表明,大型炉子和可选择性的炉子有助于生产成本的优化。由于这些小型炉子大多建于发展中国家,对发展中国家能源成本和劳动力成本增加的影响也进行了讨论。     

Corrosion of Refractory Alloys in Molten Lithium and Lithium Chloride

Abstract

Several refractory materials have been considered over the years as containment material for lithium and lithium halides. Surface modified refractory metals are being extensively investigated for containment of reactive metals, radionuclides and their compounds. An overview of experimental observations and results of liquid lithium corrosion of selected engineering refractory materials are presented. The nature of the degradation and its mechanism has been explained. The influence of temperature, microstructure, stress, impurities and service time on the corrosion behavior for various refractory alloys have been discussed. Selection rules for materials of containment for liquid lithium and lithium compounds have been suggested. Recent experimental observations on the behavior of tantalum and niobium-based refractory metal alloys in a specific molten salt environment comprising LiCl/Li₂O/Li/Li₃N at 725^°C have been included in an effort to select suitable materials for molten salt equipment. It has been observed that oxygen contamination is particularly harmful for the refractory metal alloys where as nitrogen is deleterious to iron-based alloys.     

Fusion and Dispersion of Oxide Materials in a “Cold” Crucible and in Furnaces with Concentrated Radiant Heating

Melting and dispersion of oxide materials in the system ZrO₂ - HfO₂ - Y₂O₃ is carried out in furnaces with concentrated radiant and induction heating. The polyfractional powders obtained are stabilized solid solutions of the fluorite type. A reduction is established for elementary cell parameters (from 0.5144 to 0.5127 nm) for specimens whose composition relates to an isoconcentrate with 10 mole% Y₂O₃ with an increase in HfO₂ content. Melted and dispersed ZrO₂ - HfO₂ - Y₂O₃ materials are promising for creating dense and highly refractory ceramic materials. __________ Translated from Poroshkovaya Metallurgiya, Nos. 7–8(444), pp. 36–42, July–August, 2005.     

Copper losses and thermodynamic considerations in copper smelting

A relationship between copper in slag and copper in matte during copper sulfide smelting has been derived using industrial data from 42 plants employing blast furnaces, reverberatory furnaces, flash furnaces, and Mitsubishi smelting furnaces together with the available thermodynamic equilibrium data for Cu-Fe-S-O, FeO-SiO₂, and Cu-Fe-S systems and laboratory slag-matte equilibrium information. A copper smelting diagram showing oxygen potential; sulfur potential; and copper, magnetite, and sulfur contents in slag during the smelting of different grades of copper mattes is developed for mattes containing less than 70 pct copper. The data presented can be used to determine the entrained copper losses in slag. Further, by combining the calculated value of the entrained matte with the corresponding plant data for the sulfur content of the slag, it is possible to derive the dissolved sulfur content of the slag. These calculated values were in excellent agreement with the experimentally determined sulfide capacity of fayalite slags. It is shown that there is no need to assume the presence of dissolved copper sulfide species in industrial slags. The existing equilibrium data that relate the copper content of slags to oxygen potential adequately describe the copper losses in industrial slags.     

Corrosion of Refractory Alloys in Molten Lithium and Lithium Chloride

Several refractory materials have been considered over the years as containment material for lithium and lithium halides. Surface modified refractory metals are being extensively investigated for containment of reactive metals, radionuclides and their compounds. An overview of experimental observations and results of liquid lithium corrosion of selected engineering refractory materials are presented. The nature of the degradation and its mechanism has been explained. The influence of temperature, microstructure, stress, impurities and service time on the corrosion behavior for various refractory alloys have been discussed. Selection rules for materials of containment for liquid lithium and lithium compounds have been suggested. Recent experimental observations on the behavior of tantalum and niobium-based refractory metal alloys in a specific molten salt environment comprising LiCl/Li₂O/Li/Li₃N at 725°C have been included in an effort to select suitable materials for molten salt equipment. It has been observed that oxygen contamination is particularly harmful for the refractory metal alloys where as nitrogen is deleterious to iron-based alloys.     

SPHEROIDIZATION OF IRREGULARLY SHAPED METAL POWDERS

Abstract

Irregularly shaped powders of aluminium, 90:10 bronze, 302B stainless steel, electrolytic copper, titanium, molybdenum, and tungsten carbide were converted into spherically shaped powders by dropping the powders through vertical furnaces. Several types of furnaces were built and used. The operating temperatures extended from 1650 to 3000°C, depending on the material being spheroidized, and the protective atmosphere was argon, helium, or hydrogen. The finished powders had excellent sphericity and density.     

The Influence of Slag Composition on the Corrosion of Basic Refractories

Abstract

Using a dynamic method to measure the slag resistance of refractory materials, the effect of slag composition upon the corrosion rate of a commercial basic brick has been investigated. Some recommendations are presented to improve the refractory practice of electric furnaces.

Résumé

En utilisant une méthode dynamique pour mesurer la résistance des matériaux réfractaires à l'attaque des scories d'aciérage, nous avons cherché à déterminer l'influence de la composition de la scone sur la vitesse de corrosion. A partir des résultats obtenus nous pouvons présenter quelques recommandations pour améliorer la tenue des réfractaires utilisés dans les fours électriques.     

MgO–C bricks for BOF linings

Abstract

MgO–C brick linings have become standard in basic oxygen furnaces (BOFs) all over the world. Developments in the refractory technology for BOFs over the last few years and their impact on the lifetime and performance of refractory linings are presented. These developments comprise optimised shapes for the lining of BOF and steel fibre reinforced MgO–C bricks. Optimised shapes with double wedges lead to a smooth inner surface of the refractory lining and fewer stresses and refractory consumption. Stainless steel fibre reinforced MgO–C bricks have proven to be the ultimate choice for scrap impacts or other areas with ultra high mechanical loads. They have brought down refractory wear in these particular areas significantly. Moreover, typical lining patterns of different zones in a BOF and the development of the raw material grades (MgO grades and graphite) for refractories as well as the development of lining lifetimes over the last years are discussed.     

Tribological and mechanical properties of PM journal bearings

Abstract

Powder materials are widely used in journal bearings since they provide a good tribological performance with journal bearings. These bearings are self-lubricated and can be used in places where no lubricating is possible. In this study, tribological and mechanical properties of copper based CuSn10, ferrous based Fe–graphite and copper+ferrous based CuSnFe–graphite bearings manufactured by powder metallurgy method have been determined and compared. Wear tests were carried out at 20 N load and 1500 rev min^?1 every 30 min for 2·5 h using radial journal bearing wear test rig. Hardness, tensile, compressive, bending and radial fracture mechanical tests of these bearing materials were carried out. As a result, tribological and mechanical properties improved in CuSnFe–C bearings.     

Coolant strategies for BOF steelmaking

Abstract

Thermal balance of basic oxygen furnace (BOF) steelmaking is controlled primarily by the scrap added as coolant. In the present steel scenario, insufficient availability and high cost of prime scrap has led us to explore the possibilities to use alternative coolants. Until now, choice of alternative coolants used in converter is determined by availability, price and operational strategies of the shop. These coolants have varying cooling effects and significantly influence the blowing parameters and turn-down performance. With the aim to reduce cost and dependence on prime scrap, various alternative coolants, such as iron ore lumps, pig iron, iron ore pellets, direct reduced iron and lime have been experimented with in 130 t converters under different conditions. The heat absorption behaviour and melting rate of these coolants were significantly different and found to be dependent on physical properties and addition patterns. Each coolant was individually compared for its effect on turn-down chemistry, tap temperature, slag condition and refractory wear pattern. Use of some of these coolants had beneficial effect of forming foamy slag and improved the dephosphorisation. Combined use of these coolants has helped in minimising the prime scrap requirement. This paper describes the utility of blow patterns, optimisation of coolant mix and addition strategies contrived for the synergic use of alternative coolants.     

OBSERVATIONS ON THE EFFECT OF VACUUM HEAT-TREATMENT (UP TO 4000°F) ON DISPERSIONS OF VARIOUS OXIDES,NITRIDES, AND BORIDES IN MOLYBDENUM

Abstract

The compatibility between molybdenum and several refractory compounds present as dispersed phases in the 3000-4000°F (1650–2210°C) temperature range has been evaluated. Compounds included in the study were BN, ZrN, HfN, LaB₆, ZrB₂, TaB₂, Y₂O₃, MgO, ZrO₂, and ThO₂. Hot-pressed alloys, consisting of nominally 2.5 vol.%, of the refractory phase in a molybdenum matrix, were vacuum-annealed to determine elevated-temperature stability. The evaluation was based on changes in grain size, dispersed-phase morphology, hardness, and gross macroscopic deterioration. The materials HfN, ZrO₂, and ThO₂ showed promise for dispersion-strengthening and were recommended for further development.     

火试金法测定渣选尾矿中的金量

针对闪速炼铜过程中转炉渣、闪速炉渣等再进行浮选后,其尾矿中低含量金分析方法进行探讨,确定通过加大称样量,湿法处理,活性炭吸附-火试金法和火试金重量法都可以准确测定尾矿中金含量,火试金重量法更加快速、便捷。     

Properties and microstructures of blast furnace carbon refractories with Al additions

Abstract

The effect of Al additions on the properties and microstructures of carbon refractories for blast furnaces was evaluated in terms of phase and microstructure evolutions as a function of the coking temperature. The formation and evolution of Al₄C₃, AlN and SiC crystalline phases in the matrix contribute to the excellent properties of such materials, namely high thermal conductivity and low mean pore diameter of open pores. The experimental results indicate that about 2–4 wt-%Al plus about 4–6 wt-%Si additions at ～1300°C were optimum for the manufacture of carbon refractories.     

Volatilization of bismuth in copper matte converting —computer simulation

A computer model has been developed to simulate the behavior of bismuth in copper matte converting at 1100 to 1300 °. The rate equation is integrated numerically by dividing a continuous process of matte converting into a great number of microsteps, in each of which the volatilization of Bi-bearing gases is thermodynamically calculated by assuming a steady state. The bubbles of offgas consisting of SO₂ and N₂ are assumed to be saturated with the vapors of BiS, Bi, BiO, and Bi₂. However, the partial pressures of BiO and Bi₂ are found to remain negligible at all stages of converting. BiS is the most volatile species over the slag-making stage with low grade mattes, but its volatility decreases markedly, becoming negligibly low over white metal. When the copper content of the initial matte is known together with the weight of matte, converting temperature and blowing rate of tuyere air, the present computer model can predict the Bi contents in all the phases involved (gas, slag, matte, copper) at any given time. The predictions by the present computer model are compared with the known commercial data from various smelters around the world. The agreements between the computer predictions and the commercial data are excellent in all cases, so that the present computer model can be used to monitor and optimize the bismuth elimination in the actual industrial operations of copper matte converting. Formerly Associate Professor, Department of Metallurgical Engineering, University of Utah, Salt Lake City, UT 84112.     

Oxygen probes based on calcia-doped hafnia or calcium zirconate for use in metallic melts

Up to the present, fully or partially stabilized zirconia has been used as a solid electrolyte material in probes for the determination of oxygen in metallic melts. In the present study, the ionic conduction behavior of HfO₂ (CaO) solid solutions and the compound calcium zirconate CaZrO₂ have been investigated. Both polarization experiments and EMF measurements on oxygen concentration cells point out that these two highly refractory oxide materials are also most suitable solid electrolytes. Their use is particularly recommended for oxygen probe measurements in deoxidized steel melts where extremely high chemical stability and low partial electronic conductivity of the solid electrolyte is required. In the paper, properties such as crystal structure, free energy of formation, thermal expansivity, ionic and total electrical conductivity are summarized and compared for fully and partially stabilized ZrO₂, calcium zirconate CaZrO₃, HfO₂ (CaO), and ThO₂ (Y₂O₃) solid solutions.     

A study of ancient slags from Oman

Abstract

Microscopic, chemical and X-ray techniques were used to examine slags from an extensive ancient mining site in the Persian Gulf area. The experimental results indicated that the samples were pieces of tapped slag and furnace slag from a production of copper matte. Such copper mattes could have been smelted in furnaces similar to those used during the Roman period in Timna, Israel.

Résumé

Les auteurs ont utilisé des techniques microscopiques, chimiques et de rayon-X pour examiner les laitiers provenant d'un ancien site minier de grande envergure de la région du Golfe Persique. Les résultats expérimentaux ont révélé que les échantillons étaient des morceaux de laitier de perçage et de laitier de fourneau venant de la production d'une matte de cuivre. Le smeltage de telles mattes de cuivre aurait pu se faire dans des fourneaux semblables à ceux utilises dans la période romaine à Timna en Israel.     

无液压圆盘浇铸机的研制与应用

一直以来国产的圆盘浇铸机因自动化程度低、生产效率不高、产品质量不稳定,仅限于在小型冶炼厂应用;而国内大型铜冶炼厂都是采用成套引进的国外设备。为了提高国产圆盘浇铸机的设备性能,打破国外企业的技术垄断;江西铜业集团贵溪冶炼厂通过消化、吸收国内外先进技术,采用伺服电动缸替代液压缸,开发多传感器电子秤替代进口电子秤,研制出新一代无液压圆盘浇铸机。该浇铸机的设备性能比肩国外先进设备,为国内铜冶炼厂圆盘浇铸机的新建或改造,提供了性价比更高的选项。     

THE FRACTURE-RESISTANCE OF A RANGE OF SINTERED STEELS

Abstract

The fracture-resistance of a range of sintered steels containing additions of copper and carbon has been measured in terms of their critical stress-intensity factor, K_c. All the fractures were apparently of the flat plane-strain type, the micro cracking being a process of microvoid coalescence rather than of cleavage. Toughness, in terms of K_c, is shown to depend on the percentage porosity, the level of the copper addition, and the carbon content. Higher toughness is achieved with copper + carbon additions than with either independently. A major feature of the results is that toughness increases with the yield stress, a trend that is contrary to the general behaviour of wrought materials.     

Sorptional dehydration and thermochemical sintering of converter sludge

Global steel output in 2016 exceeded 1.6 billion t, of which more than 1.2 billion t was produced in converters. The smelting of 1 t of steel produces up to 25 kg of fine dust, depending on various factors. This dust contains up to 65% iron, in oxide form. Recycling of the waste formed in steel production costs half or a third as much as the preparation of ore concentrates. For the recycling of converter sludge, methods of conditioning wet wastes by isothermal sorptional dehydration and subsequent thermochemical sintering have been developed. The adsorbent used in the present work is the solid residue from lignite pyrolysis: fine-grain lignite semicoke produced by a pilot plant at the Berezovskii-1 mine. The lignite-semicoke samples produced have a highly developed pore structure and correspondingly are characterized by excellent sorptional and energy properties. The granulometric composition of lignite semicoke is practically the same as that of the sludge. At the same time, the density of the lignite-semicoke particles is 2.5 times less than that of the sludge particles, even when the pores of the semicoke are completely filled with adsorbed moisture. On mixing the lignite semicoke and converter sludge, the semicoke absorbs moisture. The resulting mixture is highly friable, whereas the moisture adsorbed in the pores passes to the bound state and becomes an active participant in redox processes. As a result of the experiments, new material containing up to 39% Fe_met and 49% C is obtained. On that basis, an effective technology may be developed for the utilization of converter sludge to produce ferrocoke that may be employed as a fuel and reducing agent in blast furnaces and smelters. The proposed technology does not require complex mechanical and thermal dehydration and briquetting with binder.     

Slag corrosion of dolomite-carbon refractories

Seven industrial doloma refractory samples, coming from three European suppliers, and with different carbon, or graphite, or binder content, are subjected to the action of a slag required for the desulfurization of the steel in the secondary metallurgy at 1600°C. Three tests have been carried out within two induction furnaces. The corrosion depth, at the slag-steel interface, has been measured; the graphite-containing samples display a better resistance than the graphite-free pitch or resin-bonded refractories. Among the graphite-containing samples correlations have been found with the carbon content and with the resistance to oxidation by CO–CO₂ at 1100–1200°C. The slag-refractory interface has been investigated by X-ray diffraction, optical microscopy and electron microprobe analysis; the observed phases are CaO, MgO, Ca₂SiO₄, Ca₃SiO₅ and Ca₁₂Al₁₄O₃₃ (outside graphite and iron). The corrosion mechanism is linked to the reaction of slag with lime, followed by infiltration of the refractory and dispersion of periclase grains in the slag.