Manganese leaching was carried out on a small pilot scale with 110 kg of ore using manganese-reducing organisms and fermentative organisms with biomass (Typha latifolia) as the source of nutrition. This study was carried out without externally supplied chemical reagents and with minimal capital investment. The process involves fermentative organisms to ferment biomass from T. latifolia and generate organic acids. Manganesereducing organisms and organic acids reduced and dissolved manganese from pyrolusite ore. Manganese was precipitated from the manganese-bearing solution using an electrolytic oxidation technique. A manganese concentration above 500 mg/L and negligible dissolved iron was achieved at a flow rate of 30 L/ day, maintaining a pH range of 4 to 5, and a redox potential between 0.10 and 0.46 V. Manganese oxide was produced at a rate of 12 g/day, with a purity of 90 %. Amorphous manganese oxide was deposited on the cathode, while crystalline manganese oxide formed on the anode.

Rheological modifiers enable direct ink writing of polymers with low viscosity such as epoxy without requiring light or heat. Modifiers that conduct electrons and phonons impart multifunctional properties to 3D printed polymers. Here, we report the development of printable nanocomposite inks comprised of epoxy, carbon fibers (CFs), and carbon nanotubes (CNTs) to achieve excellent mechanical properties and multifunctionality via high electrical conductivity required for next -generation light weight aerospace, electronics, and energy applications. CF and CNT concentrations of 8.5 and 1.7 wt%, respectively, render the material shear -thinning with a high yield stress, hence printable and self-supporting after being printed. An average electrical conductivity of 10-2 S/cm and thermal conductivity of 0.3 W/m.K were measured for the 3D -printed multi -layer structures. Furthermore, tensile modulus, tensile strength, flexural modulus, and flexural strength were measured to be 5.8, 0.08, 6.0, and 0.1 GPa, respectively. Compared with other 3D printed conductive polymer nanocomposites with reported electrical conductivity and elastic modulus, the structures here have the highest specific elastic modulus. They also possess the highest electrical conductivity among the 3D printed polymeric composites of carbon nanomaterials with an elastic modulus above 1 GPa. This is due to the outstanding combination of CNTs, CFs, and epoxy. The results expand the range of polymer properties for multifunctional applications.

The opportunity of in situ resource utilization (ISRU) within lunar permanently shaded regions (PSRs) prompts the need for characterizing sources for excavation. The percussive heated cone penetrometer (PHCP) is an instrument being developed, through a Lunar Surface Technology Research (LuSTR) grant at Michigan Technological University (MTU) in the Planetary Surface Technology Development Lab (PSTDL), which will be able to determine the distribution of water-bearing regolith and other volatiles in PSRs. This paper explains the methodology and preliminary results of thermal profiling as well as the development of a thermal model for the PHCP that can identify the presence of volatiles in the surrounding terrain. The evaporation of various volatiles can be detected by recording the temperature as a function of time of the material surrounding the hot penetrometer and comparing the results to a dry reference material. An initial reference test setup with dry F-80 silica sand was used to determine the size of the heat-affected zone at various power levels. In two additional test series, water was then added to these sand samples to account to provide moisture levels of 5% and 10% water by weight. Temperature curves obtained from wet sand samples show plateaus due to the latent heat of vaporization, indicating the presence of water. Tests with dry, wet, and frozen lunar regolith simulant samples were then performed to refine the PHCP thermal model to provide a closer resemblance to lunar material thermal behavior. The data sets from the thermal mapping and modeling will inform the design and manufacturing of the cone penetrometer for the LuSTR project.

In situ resource utilization has long been considered crucial for sustainable human space exploration. With the confirmation of large amounts of water and water containing minerals on Mars, we are now looking at how to extract water from these sources. The most promising nonce source of water is gypsum. Pure gypsum contains 20.9% water by mass, which is released at temperatures below 210 degrees C. We have been studying an approach to mining gypsum rock (or other hydrated minerals) on Mars using a high-pressure water jet. The water jet breaks up the rock in small particles that then get pumped up in slurry form to a separation system after which the particles and adherent water get heated to release all the water in the gypsum rock particles. This water can then be recycled to the water jet or stored for creation of rocket propellant or other purposes. We found that this approach is feasible and can excavate and process the desired 1.4 kg/h water production needed to refuel a Mars Ascent Vehicle in 480 Sols for return to Earth. Water jet excavation is also less massive and has fewer wear parts than conventional mechanical excavation machines and combines the excavation, crushing, and transportation functions in one device. This paper will discuss the experimental methods, results, and a prototype design to be tested in simulated Mars environmental conditions.

The increasing demand of manganese in the industries and various hindrances in its production from low grade ores by conventional method has made it imperative for researchers around the world to develop a method of manganese extraction from low grade ores that is both environment-friendly and economical. Bioleaching has shown significant potential in manganese extraction and efficiencies of extraction have been found to be 70-98% with the help of various bacteria and fungi. This study focuses on extraction of manganese with the help of mixed bacterial strains that have been collected from their natural anaerobic environment where manganese reducing activity was evident. The extraction of manganese from reagent grade manganese dioxide and high grade manganese ore has been studied over 180 days in an anaerobic environment at room temperature and pH around 5, without the addition of any mineral acids. Highest concentrations of dissolved manganese have been found to be 928.58 mg Mn/L for reagent grade manganese dioxide and 864.54 mg Mn/L for ore grade manganese, corresponding to 650 mg and 400 mg of cumulative manganese, respectively.

With increased international interest in returning to the lunar surface and harvesting the water ice in the permanently shaded regions it is clear many uncertainties about the geotechnical properties, type and quantity of volatiles remain. Current state of the art in-situ measurements cannot uniquely determine what volatiles are present while determining geotechnical properties. No volatile release profile database exists currently. As part of the inaugural NASA Lunar Surface Technology Research (LuSTR) program, our approach to use a Percussive Hot Cone Penetrometer (DHCP) in combination with Ground Penetrating Radar (GPR) was selected for funding. The team from Michigan Technological University (MTU) and Honeybee Robotics (HBR) will perform this work in two years from 2021-2023. This paper will describe the progress made over the initial summer testing.

Water exists in various forms on Mars. Polar ice caps, buried glaciers, frozen groundwater and hydrated minerals where the water is bound in the mineral structure all can be found in different places. This water can be extracted using different methods and then cleaned and electrolyzed to create liquid oxygen and hydrogen or combined with atmospheric carbon dioxide to create oxygen and methane for rocket propellant. One promising candidate for water extraction from hydrated minerals is gypsum. Gypsum consists of calcium-sulfate and has 2 molecules of water bound in the mineral crystal structure which in practice means that gypsum is about 20% water by weight. From previous studies it was found that water extraction from gypsum is energetically and mass wise the most economical unless direct water ice can be accessed which due to special regions classification may be challenging at first. As part of a NASA Early Stage Innovation grant, a team of researchers from Michigan Technological University (MTU) and Honeybee Robotics (HBR) has been developing technology to excavate gypsum rock and extract water from it. The method that has been developed and tested is based on disaggregation of the gypsum by using a water jet system inside an enclosure to contain the splashing water and maintain a pressure of at least 3kPa to assure water stays liquid. The resulting small gypsum particles and water mixture, the slurry, is sucked into a gravity separation system where most of the liquid water is syphoned off and recycled back to the water jet while the gypsum particles and the remainder of the liquid water are transferred into the reactor vessel and heated to 210C to extract all the liquid water and crystalline bound water. The water vapor is then condensed and captured to feed back into the water jet reservoir and the excess stored for further processing in the cleaning and electrolyzer unit or the Sabatier reactor, depending on what kind of rocket propellant needs to be produced. This paper will discuss the design, development, subsystem testing and relevant environment testing at MTU and HBR. We will discuss each of the subsystems, sizing of the system, energy efficiency and how many variables will affect the excavation process and their testing results up to Technology Readiness Level 4 (TRL-4) which requires subsystem testing in relevant conditions as well as modeling.

Roasting followed by acid leaching has long been an established dephosphorization technique for processing the goethite iron ore in the past. However, given the high-energy requirement in the process, there still exists further room for improvement. The present study of phosphorus removal from an unroasted iron ore via alkaline leaching method examined the possibility of dephosphorization from goethite ore at low temperature. The iron ore concentrate used in this study is an oolitic type of iron ore consisting primarily of goethite, in which phosphorus does not form a discrete mineral phase, but instead is diffused throughout the entire volume of the ore. This study reveals that the reduction of particle size, the increase in both temperature and hydroxyl ion [OH-] concentration all promote phosphorus removal. About 50% of the phosphorus can be removed in relatively low [OH-] concentration (1.25 M), about 80% phosphorous removal was attained after further increasing the [OH-] concentration to 15 M resulting in 0.1% phosphorus in final solids with no iron losses, which was comparable to roasting followed by acid-leaching route. The optimum conditions was identified as temperature of 85 degrees C, [OH-] concentration of 15 M, 0.025-0.038 mm particle size, and 10 min of leaching time with S/L ratio of 0.25 g/ml, in which P level can be reduced from 0.73 to about 0.1 wt%P. Additionally, leaching solution was demonstrated to be readily regenerated using hydrated-lime with comparable leaching ability in terms of phosphorus removal compared to fresh solution. No significant mineralogical change observed other than the uniform removal of phosphorus during the process.

Phosphorus has been long recognized as an unwanted element in steelmaking, which should be kept as low as possible. In current study, bio-extraction of phosphorus from goethite ore by naturally existed alkaline-tolerant microorganisms was investigated. The microbial growth, medium pH, and phosphorus extraction were monitored. It was found that alkali addition did not possess any positive effect on either microbial growth or phosphorus extraction as a whole. Medium pH was readily reduced from initial 8.5 to 4-6, on the other hand, constant alkaline condition was observed to largely inhibit most of microbial activities. A negligible amount of phosphorus was detected in liquid medium, therefore most of the phosphorus removal was attributed to phosphorus uptake for cell growth. Completing 45-day of incubation, the phosphorus content were reduced from initial 0.73% P to an average of 0.59% and 0.63% P by microorganisms obtained from two different sites, which were equivalent to 19% and 14% phosphorus removal. The highest phosphorus removal (38.4%) was correlated to a "massive" biomass development. It was also observed that fungus were favored over bacterium when pH was below 6.5. However, there are still some questions and uncertainties remaining in future regarding bio-beneficiation including: the complexity of microbial growth and reproducibility concern, lack of quantitative analysis and control methods, and the organic carbon requirement.

Sodium hydroxide (NaOH) is known to be capable of selectively leaching phosphorus from oolitic iron ores. The main limitation on implementing this leaching approach is the expense of NaOH. In order to make sodium hydroxide leaching practical, a method is needed for removing the dissolved phosphorus from solution and inexpensively regenerating the sodium hydroxide. In this work, removal of phosphorus from solution was achieved using calcium hydroxide (Ca(OH)2), which is significantly less expensive than NaOH. The addition of Francolite seed crystals greatly accelerates the precipitation rate. Up to 99.9% of phosphorus in solution was removed within thirty minutes. A leaching comparison between fresh and regenerated caustic solution was performed, with removal rates of 51.9% and 52.2% respectively, demonstrating that the regenerated leaching solution was still effective for removing phosphorus.

Since mercury is chemically similar to silver, it tends to dissolve along with the silver and gold during cyanide leaching. Ultimately, mercury is recovered along with the silver as mercury/silver/gold amalgam, which requires retorting to remove the mercury prior to refining the silver and gold. A possible approach to separating mercury from silver and gold in cyanide leach solutions is to take advantage of the replacement reaction between [Hg(CN)4]2− and Ag2S, which results in precipitation of mercury as HgS while dissolving silver as [Ag(CN)2]− Results are presented demonstrating that mercury can be removed from cyanide solutions with high effectiveness while, at the same time, recovering additional silver in solution. Initial experiments with static flasks in the laboratory showed a high degree of mercury removal could be achieved. Results using actual metallurgical plant products in bottle roll tests indicate the process works on a larger scale, but also results in significant gold losses if the solution being treated has high gold levels, such as carbon stripping pregnant eluent solution.

Bentonite is a predominant binder used in iron ore pelletization. However, the presence of a high content of silica and alumina in bentonite is considered undesirable for ironmaking operations. The objective of this study was to identify the alternatives of bentonite for iron ore pelletization. To achieve this goal, different types of organic and inorganic binders were utilized to produce iron oxide pellets. The quality of these iron oxide pellets was compared with pellets made using bentonite. All pellets were tested for physical strength at different stages of pelletization to determine their ability to survive during shipping and handling. The results show that organic binders such as lactose monohydrate, hemicellulose, and sodium lignosulfonate can provide sufficient strength to indurated pellets.

Selective removal of mercury from cyanide leaching solutions while retaining silver has been a long-standing problem, due to the chemical similarity of mercury and silver. In order to be practical, a mercury removal process needs to be both highly selective and use inexpensive materials. This paper reports the use of zinc sulfide (ZnS) as a precipitant for mercury. The mercury cyanide complex (Hg(CN) 4 2− ) undergoes a replacement reaction with the zinc sulfide, forming insoluble HgS, while the silver cyanide complex (Ag(CN)2−) remains in solution. Under appropriate conditions, the separation of mercury from silver is nearly quantitative, with close to 100% removal of mercury, while nearly none of the silver is precipitated.

Leaching of iron, either as an impurity to be removed or as a metal to be recovered, requires a different approach than that of the oxidative leaching that dominates biohydrometallurgy of other metals. In particular, the significant increase in solubility that results from reducing Fe3+ to Fe2+ suggests that a reductive leaching process is most suitable. A wide range of anaerobic iron-reducing bacteria have been demonstrated to exist in the last few decades, which reduce Fe3+ to Fe2+ as part of their respiration. More of these organisms are continually being discovered, and many of these have promise for reductive bioleaching of iron. This review examines the many types of bacteria that have been demonstrated to reduce and solubilize iron, and the environments where such organisms can be found. The cultivation requirements of these organisms are also discussed, along with descriptions of the work that has been done to apply them to specific applications. These applications include decolorization of kaolin and silica, iron removal from bauxite, recovery of iron from low-grade or difficult-to-process ores, and promoting breakdown of iron-rich rocks to liberate other metals. Reductive iron leaching in these applications has been shown to be most effective for dissolving the more hydrated and amorphous iron oxides, with low dissolution rates for highly crystalline oxides such as hematite. It has also been shown that, the given sufficient adaptation and leaching time, these microorganisms can produce iron-bearing solutions containing as much as 1800mg of Fe2+ per liter.

Iron ore pellets must have sufficient mechanical strengths against degradation in all stages of pellet production. Low strength is also a problem for product pellets since they abrade during transportation to the reduction furnaces. The use of a binder is necessary to provide sufficient strength to the pellets and for better operation and handling of pellets. Bentonite is the standard binder in the industry; however, it is considered an impurity due to its acid oxide contents. Organic binders have been tested for many years as alternative binder to bentonite. They have been found to give sufficient wet pellet properties. However, they failed to provide sufficient strength to the preheated and fired pellets due to lack of slag bonding. It has been assumed that one possible effective method to improve the preheated and fired pellet strengths is addition of a slag-bonding constituent. In this study, calcined colemanite was added to the pellet feed to overcome the lower strength problem encountered with organic binder use. The strength of pellets produced with organic binders and calcined colemanite alone and in combination was comparatively studied against the strength of pellets made with standard bentonite binder in magnetite concentrate pelletizing. The results showed that addition of calcined colemanite into the pellet mixture improved the preheated and fired pellet strengths of pellets produced with organic binders.