Materials Engineering—From Ideas to Practice: An EPD Symposium in Honor of Jiann-Yang Hwang

Dr. Jiann-Yang Hwang served as the Director of the Institute of Materials Processing at Michigan Technological University for more than 20 years. Many technologies have been developed from ideas to commercial practices in his career life. This symposium reflects his contributions in this aspect. The cycle of materials such as metals on the earth involved the steps of ore exploration (geology), mining, mineral processing, metallurgy, manufacturing, and recycling. Each step is achieved by processing materials using energy. Depending on the process and the forms of energy input, products, and by-products with various environmental impacts are generated through air, water, and solid means. To obtain the most efficient process with the minimum environmental impacts at the best economics is the driving force that continuously pushes the advances of technologies. Variables in the materials, process, and energy are common parameters facilitating the development of ideas for technology advancements. Dr. Hwang learned earth sciences, mineralogy, characterization, mineral processing, and metallurgy during his undergraduate and graduate studies. Mining, materials, and processing, and environmental and economics are mostly self-studied at postgraduate time, partly pushed by the research needs from projects he wanted to conduct. Understanding the parameters involved in the materials, energy, environment, and economics is fundamental to a systematic approach. The validity of ideas and their potential to move to practice depend on the soundness of the system. The author reviewed several cases of his research to illustrate their relations.

In this paper, the method of preparing green balls from Brazilian iron concentrate was studied. The hematite and two kinds of magnetite concentrate were the main raw materials, the effects of the dosage of bentonite, pelletizing moisture, pelletizing time, particle size, and the ratio of the two magnetite concentrates on the green balls’ strength were studied. When using 1.0–1.3% Indian bentonite, the pelletizing moisture of 9.5–10%, the pelletizing time of 12–15 min, the mineral powder particle size under the condition of −325 mesh 85–90%, it is suitable for pelletizing. And the falling strength of the green balls is 3.0 times 0.5 m⁻¹, the compressive strength is 16–23 N/P, the decrepitation temperature of the green balls is above 350 ℃. After blending with the magnetic concentrate, the decrepitation temperature of the green balls rises, but the strength decreases, and the amount of bentonite needs to be increased.

Microwave-assisted pyrometallurgy has many distinguished advantages over traditional pyrometallurgical processes. In the past 5 years, the researchers at Central South University (CSU) has been focusing on the use of microwave energy for intensifying various pyrometallurgical processes for higher processing efficiency, enhanced metal recovery, lower energy consumption, and better environmental benefits. This study reviewed the efforts of the researchers at CSU in microwave-assisted pyrometallurgy for treatment of wastes, with an aim to offer a useful guide for improving the technology.

In order to reduce the fuel rate of blast furnace and promote green development, Shougang Jingtang Steel company has built two straight grate indurating machines with a productivity of 8 million tons of iron ore pellets. In this paper, the production technologies of self-fluxed pellets with hydrated lime were studied and the high-quality pellets were successfully produced on the indurating machine. Hydrated lime has a good binder property and decreases the amount of bentonite to obtain low silica pellet. The basicity is 1.15 and SiO₂ content is 2.0% in the pellet. The low-silica self-fluxed pellets were used in three large blast furnaces with 5500 m³ in Shougang Jingtang. The proportion of pellets in burden increased from 28 to 55%, slag rate of blast furnace decreased from 280 to 215 kg/tHM, and the fuel rate decreased from 500 to 480 kg/tHM.

A typical cation exchange membrane can be prepared from graft polymerization of styrene onto low-density polyethylene followed by sulfonation reaction. It was found that the thermoplastic elastomer polystyrene-block-poly(ethylene-ran-butylene)-block-polystyrene (PS-PEB-PS) can be blended with polyethylene-graft-polystyrene (PE-g-PS) in toluene. A novel composite cation exchange membrane was prepared by sulfonating the membrane cast from the mixture solution of PE-g-PS and PS-PEB-PS. Compared with the non-blended cation exchange membrane, the blending of 10% PS-PEB-PS enhanced the ion exchange capacity, water uptake, and Mullen burst strength of the cation exchange membrane by 18.3%, 9.5%, and 26.3%, respectively. The blending also lowered the thermal expansion rate by 73.4%, making the membrane more thermally stable over temperature increase.

This paper introduces a pilot plant test of pig iron nuggets and syngas productions using a microwave plasma rotary hearth furnace (MW/PA-RHF). In addition, the furnace is integrated with a bag house, a H2S wet scrubber, a syngas compressor, two syngas storage tanks, and a syngas monitoring system to process the produced syngas. Limited tests showed molten pig iron nuggets and syngas can be produced concurrently using this integrated system.

Pyrometallurgical route is the most effective way to extract copper from Cu–Fe–S ores. In the smelting process, the concentrate is partially oxidized to Cu-rich matte and most of the impurities are reported to the slag. Copper content in the slag represents the direct recovery of copper in the smelting process. High-temperature experiments have been carried out to investigate the effects of slag composition, matte grade, and temperature on copper content in the smelting slag. Industrial and synthetic slag samples were equilibrated with matte at different temperatures in argon gas flow. The quenched samples were analysed by electron probe X-ray microanalysis to obtain the microstructure and phase compositions at high temperatures. Optimised parameters including slag composition, matte grade, and temperature have been proposed for the flash smelting furnace operations to minimize the copper content in the slag. The experimental results are also compared with the FactSage calculations.

Pellet is one of the important feeds to iron blast furnace and increased proportion of the pellet is used around the world. Pellet production is cleaner than sinter and its uniform properties allow stable blast furnace operations. Boron iron concentrate is a by-product during production of boron and contains approximately 54% Fe, 3–6% B₂O₃, and 10% MgO. B₂O₃ can form liquid binding phase inside the pellet at relatively lower temperature which reduces the fuel and refractory consumption during the pellet production. MgO can reduce the reduction expansion rate of the pellets. Effects of boron iron concentrate, preheating temperature, and time on the strength of the preheated pellet have been investigated. It was found that the compressive strength of the preheated pellet with addition of boron iron concentrate was increased with increasing preheating temperature and time. When the pellets were preheated at 1030 °C for 25 min, the strength of the pellets with 50% boron iron concentrate can reach more than 600 N/P. The optimized parameters can significantly increase the strength of the pellet and reduce the loop formation of the rotary kiln.

In this paper, the method of preparing roasted pellets in a tube furnace is studied. In order to meet the performance standards of blast furnace ironmaking finished pellets, the compressive strength of the pellets must be above 2500 N/P. Hematite and magnetite were used as the main raw materials. The effects of preheating temperature, preheating time, roasting temperature, roasting time and the ratio of magnetite concentrate on the strength of pellets were studied. Under the conditions of preheating temperature of 975 ℃, preheating time of 15 min, roasting temperature of 1300 ℃, roasting time of 15 min, and the proportion of magnetite concentrate of 20–30%, the compressive strength 4948.3 N/P of roasted pellets was reached, thus meeting the performance indicators.

Application of a long life and low-cost metallic electrode in salt bath heat treatment, all-electric glass smelters, and primary aluminum production has potential advantages, including great energy saving, significant environmental benefits, adequate electric conductivity, high fracture toughness, excellent thermal shock resistance, and ease of fabrication into complex shapes. Nickel-based alloys have been used in a wide variety of severe operating conditions involving corrosive environment, elevated temperature, high stress, and their combinations. To estimate the feasibility of nickel-based superalloy used as an electrode material, the erosion rate of an Inco nickel-based superalloy in a standard fluoride electrolyte melt was investigated. The diffusion speeds of the metals are in a sequence of Cr > Ni > Fe > Mo. The maximum erosion rate of the superalloy in the fluoride at 1000 ℃ is approximately 27 μ per hour in a three hours period.

This study is to explore the feasibility of iron and syngas co-production from iron ore and pulverized coal mixture in an enclosed vessel using microwave heating. Reactions take place after the materials are subjected to heating above certain temperatures. Coal serves as the reducing agent for iron oxide and the source of carbon and hydrogen for the syngas generation. The iron oxide serves as the iron source for steelmaking as well as the oxygen source for the carbon partial reaction to form CO. In comparison with conventional coal gasification, the oxygen comes from iron oxide instead of pure oxygen separated from the air. This study showed that direct reduced iron with over 95% metallization and syngas with total concentration of CO and combustibles over 80% were readily produced.

The third phase is generated inevitably, but affects the quality of the electric nickel product in the nickel metallurgical process. This paper studies the formation and the prevention mechanism of the third phase in the raffinate. The analysis of Fe-S–Si-H₂O system shows that iron exists in the form of Fe³⁺ at the pH value ≤ 2.17. With pH increasing, Fe³⁺ begins to hydrolyze to form FeOH²⁺. FeOH²⁺ continues to hydrolyze to form Fe(OH)₂⁺ at the pH value ≥ 4.72. Fe³⁺ is reduced and hydrolyzed to FeOH⁺ when the potential ≤ 0.21 V. The precipitation of Fe₂SiO₄ is reduced at the potential ≤ 0.35 V and 5 ≤ pH value ≤ 13.2 when the solution contains silicon dioxide. The analysis of the third phase shows that it is mainly iron hydroxide, iron polynuclear hydroxyl complex ions, and Fe-SO₄ complexes. It provides theoretical guidance for the formation of the third phase in the extraction multiphase system. This also plays a positive role in the production of high-quality nickel products.

Thermo-Calc software is used to reassess the equilibrium temperature-composition phase diagram at 1 atm and to deduce the thermodynamic properties of Cu–O binary system at T = 1500 K. The phase diagram showed one single phase which is the non-stoichiometric Cu ionic liquid other than elemental Cu and O at the terminals, in addition to Cu₂O and CuO which can be considered as stoichiometric line compounds. There are nine fields of two mixed phases, two eutectic reactions, one monotectic reaction, and a miscibility gap. The solubility of oxygen in copper and that of copper in oxygen are determined. The molar Gibbs energy and molar enthalpy curves of the Cu₂O–CuO ionic solution are plotted against mole fraction oxygen at 1500 K. The natural logarithm of the activity is plotted against oxygen mole fraction for oxygen and copper in the melt, and the activity coefficients are determined.

The low-silica and low basicity sintering is an effective measure for improving iron grade of sinter and reducing the slag amount of ironmaking and steelmaking. Sintering of the mixture at basicity (1.9, 1.8, and 1.7) and SiO₂ content (5.0, 4.9, 4.8, 4.7, and 4.6) were conducted in a sintering pot, and the microstructures of typical sinters were taken into comparison in this work. Experimental results show that with the basicity decreases from 1.90 to 1.70, there is an obvious change in the tumbler strength index (TI) of sinter; SiO₂ content affects mainly on the yield, but to a lesser extent on the TI of sinter. At the basicity of 1.70 and SiO₂ content of 4.60%, the TI of sinter is 58.53% which is 5% lower than the sinter at basicity of 1.90 and SiO₂ content of 4.98%. At basicity of 1.80 and SiO₂ content of 4.60%, the sinter obtains a good performance (yield of 76.07% and TI of 60.09%), which is close to the indexes of sinter at relatively high-silica and high basicity ( basicity of 1.90 and SiO₂ content of 4.98%), indicating that low SiO₂ content and low basicity sintering can be implemented.

In this paper, three different processes—chelation accompanied by oxidation, oxidation followed by chelation, and oxidative acid leaching followed by chelation—are designed for extraction of zinc from oxide-sulphide zinc ore, and through a comparison of the redox potentials, suitable oxidation additives are determined for each process. Besides, effects of oxidant additives doping level on zinc recovery are investigated. The results show that the zinc leaching degree can reach 83.72% with addition of NaO being 0.3 mol/L in the process of chelation accompanied by oxidation, the zinc leaching degree can reach 92.40% with NaO adding 0.5 mol/L in the process of oxidation followed by chelation, and the zinc leaching degree can reach 93.02% under a condition of NaClO doping level being 0.1 mol/L in the process of oxidative acid leaching followed by chelation. All three processes prove their value on extraction of oxide-sulphide zinc ores.

The evaluation method for pulverized coal injection in blast furnace including parameters of blast volume, pressure difference, gas dust production, quality, etc. was developed in this work. Indexes for smooth operation of blast furnace and utilization of PCI (pulverized coal injection) coal (named carbon content index) were also proposed. The evaluation method can reflect the effect of type of pulverized coal on the utilization ratio of pulverized coal and the blast furnace performances. The industrial trial showed that when 10% Coal B was used, smooth operation index reduced by more than 0.05 and carbon content index increased by over 1.0, which indicated that coal B could not be used too much in PCI. When coal A was used up to 35%, smooth operation index increased 0.08 and carbon content index reduced by over 0.22 with blast furnace output and coal ratio increasing, which meant that Coal A was suitable for PCI.

“FeO”-SiO₂ slags account for a fundamental system in many metallurgical processes and geology, while the slag structures are rarely investigated. In this study, the structures of the quenched “FeO”-SiO₂ slags were quantitatively clarified using the Raman spectra. The samples were equilibrated with metallic iron at high temperatures and quenched rapidly to maintain their structures for examination at room temperature. It was found that as the “FeO” content was 70 wt%, four separate peaks assigned to different SiO₄ tetrahedral appeared at −820, −850, −890, and −950 cm⁻¹ in the Raman spectra, which provided a direct clue for the further Raman devolutions. As the “FeO” content increased to 85 wt%, only Q⁰(Si) isolations were present in the networks. Raman devolutions showed that with increasing “FeO” content, the mole fraction of Q⁰(Si) increased, while those of Q²(Si) and Q³(Si) decreased. Furthermore, the relationship between structures and viscosities was discussed, which deepened the knowledge of this fundamental system.

There are abundant strategic rare-scattered metal resources in lead and zinc deposits in China, especially zinc resources in Yunnan province, which are associated with indium (In), selenium (Se), tellurium (Te), etc. Small amounts of these rare-scattered metal ions are dissolved into zinc acidic leaching solutions, and are difficult to remove by conventional zinc powder replacement. They are enriched in the ZnSO₄ solution, which causes serious problems to the zinc electrowinning process such as hydrogen generation, zinc re-dissolution, plate burning, low current efficiency, etc. So, they need to be deeply purified from ZnSO₄ solution. This article used ozone, a strong oxidizing agent, to make oxidative precipitation of the impurities from ZnSO₄ solution. The effects of reaction temperature, ozone flow rate, and residence time on In, Se, and Te removal together with the associated Mn removal and Zn loss were investigated. The ozonation reaction kinetics was evaluated by plotting the negative logarithm of the metals in solution concentration as a function of reaction time. One precipitate prepared at optimized conditions was characterized by XRD, EDS, and SEM to identify the chemical compounds and morphology.

The objective of this study is to evaluate the effect of temperature on the leachability of chromium in EAF slag. Mineral phase identification and micromorphology analysis were used to study the distribution of chromium in the EAF slag and the leaching residue. Sequential leaching tests were performed to study the chromium leachability in EAF slag under different temperature. The results show that the chromium in the EAF slag was mainly present in the Mg-Cr spinel, Fe–Cr alloy, or distributed in the form of oxide in the matrix phase-merwinite. In the sequential leaching process, the leachates under various temperatures were all alkaline and reductive. The release rates of chromium could reach their equilibrium values when the leaching time reached to 48 h, and the trivalent chromium was the predominant speciation of chromium in the leachates. The leachability of chromium in EAF slag decreased gradually with increasing temperature.

Electroplating is critical to the manufacturing but has been unwelcome to local government and residents due to its potential to cause serious environmental pollution. There are many kinds of plating, such as copper, nickel, zinc, and chromium based on the kinds of metal plated, or other varieties based on the plating methods or additives. An industrial park to house a variety of electroplating industries together has been proposed and developed. This approach provides professional operations to manage and treat the complicated environmental issues that most electroplating plants have difficulties to handle. Examples of these operations are provided.

Electroplating is one of the most important parts in the modern manufacturing industry. All of our modern electronics need some sort of electroplating process to help it achieve its goals. From smartphone, computer, heavy machinery, decoration, to motor vehicle, almost everything that we used nowadays need electroplating in some ways. However, at the same time electroplating factory can do much harm to the natural environment. Electroplating industry produce 2.7 billion gallons of wastewater in China every year. And most of it won’t be treated to the required level and all go to the river and ocean. This causes a big issue for the environment. Dr. Hwang and Futianbao Environment Protection Technology Ltd. developed a new way to treat the electroplating wastewater. We called it “SCR”, “S” means separation, “C” means concentration and “R” means recycle. The world leading edge “SCR” technology was successfully developed in 2016 by our R&D team which leads by Dr. Hwang. This technology comprehensively not only uses various physical and chemical separation technologies to achieve salt concentration and crystallization, but also recycles heavy metal from the wastewater and reuse reclaimed water. This technology meets the “zero emission” requirement in China. At the same time, it achieves the goal of harmful waste reduction and resource recycling.

This study explores a new electroplating wastewater treatment process which could be cheaper and more efficient than the conventional approaches. The process consists of 3 steps: (1) electric lime is added to the electroplating wastewater to adjust the pH to around 9; (2) activated carbon is added to the turbid liquid; and (3) vacuum filter is used to replace traditional sedimentation tank for solid–liquid separation. Electric lime is used to replace liquid alkali for pH adjustment, which can greatly reduce production cost. Compared with the traditional sedimentation tank, the vacuum filter occupies less space, has lower operating cost and higher filtration speed, which greatly improves the production efficiency. The effluent of treated electroplating wastewater using the new process has the COD content reduced by about 60%, and the total oil content reduced by about 80%. This is obviously better than the traditional treatment process.

The electroplating industry is one of the surface treatment industries with strong versatility and a wide application range. The electroplating process mainly includes pretreatment, electroplating, and post-treatment. In order to achieve specific effects, additives such as brightener, subbrightener, surfactant, and others are indispensable in the electroplating process. These organics usually have poor biodegradability. In addition, due to the high toxicity of electroplating wastewater, biological treatment has great limitations on their decomposition. These organic compounds cause the increase of COD in electroplating wastewater, which seriously pollutes the membrane system and hinders the development of electroplating wastewater reuse process. In this study, ozone is investigated for the oxidation of organics and the results are discussed.

Copper was widely used in electroplating, and a lot of wastewater was produced in the rinsing process. Copper-containing electroplating wastewater can be divided into cyanide wastewater and copper sulfate wastewater according to the difference of plating process. This study is to explore the feasibility of cyanide oxidation and cupric reduction in an electrochemical reactor using an anion exchange membrane as the diaphragm. In the anolyte compartment cyanide in the cyanide wastewater was oxidized to cyanate, and furthermore, to carbon dioxide and nitrogen. In the catholyte compartment cupric in the copper sulphate wastewater was restored to copper. This study showed that the dosage of sodium hypochlorite used in the cyanide oxidation was decreased from 95 to 15 g/L and over 80% copper was recovered from copper sulphate wastewater by electrolysis.

Automobile exhaust catalyst has been more and more widely used for creating a green life. It contains abundant platinum, palladium, rhodium, and rare earth cerium, compared with primary resources. It’s necessary to efficiently recover valuable metals with great application value. The feasibility of leaching cerium from hydrochloric acid system is mainly analyzed from the perspective of thermodynamics in this paper. The leaching experiment of hydrochloric acid oxidation is carried out. The results show that the leaching rate of cerium reaches only 46% when the concentration of hydrochloric acid was 4 mol/L, the reaction temperature was 80 °C, the amount of hydrogen peroxide was 10 ml, the liquid–solid ratio was 10:1, the reaction time was 2 h, and the stirring speed was 450 r/min. According to the metal equilibrium, it is inferred that the formation of stable Ce–Zr solid solution makes the lower leaching rate of cerium.

Electroless nickel plating technology is also called chemical nickel plating, which is an important nickel plating method. However, the wastewater produced by electroless nickel plating contains a large amount of phosphorus and nickel. The heavy metal nickel is carcinogenic and has sensitizing effects. It is also toxic to environmental organisms. Phosphorus is a well-known factor that leads to eutrophication of water bodies. How to effectively deal with the waste solution of chemical nickel plating, turning the environmental pollutants into recyclable resources, and reducing the damage to the ecological environment are of great significance. This article applies ozone to the treatment of nickel wastewater. Its success brings the possibility of developing a new method for the treatment of nickel wastewater.

Degreasing wastewater is a common type of wastewater produced from surface degreasing process in the electroplating industry. It has the characteristics of high pH, high oil content, and high COD value. This paper studies COD reduction of degreasing wastewater by UV/H₂O₂ oxidation process, and factors that affect COD removal rate. Those include H₂O₂ dosage, feeding method, and pH value. The optimized reaction condition was found to be pH of 3, the molar ratio of H₂O₂ to COD at 1:1 with continuous feeding of H₂O₂. A maximum COD removal rate of 91% can be achieved after 4 h of reaction.

In continuous annealing furnace for low-temperature grain-oriented silicon steel production, carbon sleeve is used as one kind of the best hearth rolls to support and convey steel strip. However, the surface of carbon sleeve in nitriding zone is seriously corroded after a period of time, the surface roughness of carbon sleeve increases, the edge wears and even buildups appear, which seriously affects the surface quality of products. Based on the working conditions of carbon sleeve, the causes and mechanism of corrosion on carbon sleeve by ammonia, and effects of antioxidants on surface quality of low-temperature grain-oriented silicon steel are discussed. In terms of the resistance to ammonia, phosphate is not a good antioxidant for carbon sleeve in continuous annealing furnace for low temperature grain-oriented silicon steel production.

The objective of this work was to evaluate the influence of photodegradation by ultraviolet radiation in composites of epoxy matrix reinforced with sisal fabric in the energy absorption capacity against shots of 0.22-gauge lead projectile. The ballistic tests were performed at subsonic speed using a 150-bar compressed air draft system. The ballistic efficiency was evaluated using the residual velocity technique. Fourier transform infrared spectroscopy (FTIR) was also performed to observe changes after radiation exposure. Exposure to UV radiation, both at 75–225 h, caused changes in the color of the composite plates, in addition to optimizing the energy absorption capacity in level I events by NIJ 0101.04, absorbing about 93% of the projectile energy, showing to be a very easy and fast technique for improving the ballistic properties of composites which in turn are more economically viable than the commonly used synthetic materials.