A New Method for Production of Titanium Dioxide Pigment - Eliminating CO2 Emission

The objective of this project was to demonstrate the potential of a new process technology to reduce the energy consumption and CO{sub 2} emission from the production of titanium dioxide (TiO{sub 2}) pigment. TiO{sub 2} is one of the most commonly used minerals in the chemical manufacturing industry. It has been commercially processed as a pigment since the early 1900's, and has a wide variety of domestic and industrial applications. TiO{sub 2} pigment is currently produced primarily by the use of the so called �chloride process�. A key step of the chloride process relies on high temperature carbo-chlorination of TiO{sub 2} bearing raw materials, hence producing large quantities of CO{sub 2}. The new method uses a chemical/metallurgical sequential extraction methodology to produce pigment grade TiO{sub 2} from high-TiO{sub 2} slag. The specific project objectives were to 1) study and prove the scientific validity of the concept, 2) understand the primary chemical reactions and the efficiency of sequential extraction schemes, 3) determine the properties of TiO{sub 2} produced using the technology, and 4) model the energy consumptions and environmental benefits of the technology. These objectives were successfully met and a new process for producing commercial quality TiO{sub 2} pigment was developed and experimentally validated. The process features a unique combination of established metallurgical processes, including alkaline roasting of titania slag followed by leaching, solvent extraction, hydrolysis, and calcination. The caustic, acidic, and organic streams in the process will also be regenerated and reused in the process, greatly reducing environmental waste. The purpose and effect of each of these steps in producing purified TiO{sub 2} is detailed in the report. The levels of impurities in our pigment meet the requirements for commercial pigment, and are nearly equivalent to those of two commercial pigments. Solvent extraction with an amine extractant proved to be extremely effective in achieving these targets. A model plant producing 100,000 tons TiO{sub 2} per year was designed that would employ the new method of pigment manufacture. A flow sheet was developed and a mass and energy balance was performed. A comparison of the new process and the chloride process indicate that implementation of the new process in the US would result in a 21% decrease in energy consumption, an annual energy savings of 42.7 million GJ. The new process would reduce CO{sub 2} emissions by 21% in comparison to the chloride process, an annual reduction of 2.70 million tons of CO{sub 2}. Since the process equipment employed in the new process is well established in other industrial processes and the raw materials for the two processes are identical we believe the capital, labor and materials cost of production of pigment grade TiO{sub 2} using the new method would be at least equivalent to that of the chloride process. Additionally, it is likely that the operating costs will be lower by using the new process because of the reduced energy consumption. Although the new process technology is logical and feasible based on its chemistry, thermodynamic principles, and experimental results, its development and refinement through more rigorous and comprehensive research at the kilogram scale is needed to establish it as a competitive industrial process. The effect of the recycling of process streams on the final product quality should also be investigated. Further development would also help determine if the energy efficiency and the environmental benefits of the new process are indeed significantly better than current commercial methods of pigment manufacture

Low-Temperature Synthesis of Superconducting Nanocrystalline MgB

Magnesium diboride (MgB2) is considered a promising material for practical application in superconducting devices, with a transition temperature near 40 K. In the present paper, nanocrystalline MgB2 with an average particle size of approximately 70 nm is synthesized by reacting LiBH4 with MgH2 at temperatures as low as 450°C. This synthesis approach successfully bypasses the usage of either elemental boron or toxic diborane gas. The superconductivity of the nanostructures is confirmed by magnetization measurements, showing a superconducting critical temperature of 38.7 K

Review of the Methods for Production of Spherical Ti and Ti Alloy Powder

Spherical titanium alloy powder is an important raw material for near-netshape fabrication via a powder metallurgy (PM) manufacturing route, as well as feedstock for powder injection molding, and additive manufacturing (AM). Nevertheless, the cost of Ti powder including spherical Ti alloy has been a major hurdle that prevented PM Ti from being adopted for a wide range of applications. Especially with the increasing importance of powder-bed based AM technologies, the demand for spherical Ti powder has brought renewed attention on properties and cost, as well as on powder-producing processes. The performance of Ti components manufactured from powder has a strong dependence on the quality of powder, and it is therefore crucial to understand the properties and production methods of powder. This article aims to provide a cursory review of the basic techniques of commercial and emerging methods for making spherical Ti powder. The advantages as well as limitations of different methods are discussed.</p

Roles of Ti-Based Catalysts on Magnesium Hydride and Its Hydrogen Storage Properties

Magnesium-based hydrides are considered as promising candidates for solid-state hydrogen storage and thermal energy storage, due to their high hydrogen capacity, reversibility, and elemental abundance of Mg. To improve the sluggish kinetics of MgH2, catalytic doping using Ti-based catalysts is regarded as an effective approach to enhance Mg-based materials. In the past decades, Ti-based additives, as one of the important groups of catalysts, have received intensive endeavors towards the understanding of the fundamental principle of catalysis for the Mg-H2 reaction. In this review, we start with the introduction of fundamental features of magnesium hydride and then summarize the recent advances of Ti-based additive doped MgH2 materials. The roles of Ti-based catalysts in various categories of elemental metals, hydrides, oxides, halides, and intermetallic compounds were overviewed. Particularly, the kinetic mechanisms are discussed in detail. Moreover, the remaining challenges and future perspectives of Mg-based hydrides are discussed

A study on the synthesis of coarse TiO2 powder with controlled particle sizes and morphology via hydrolysis

The hydrolysis of Ti(IV)-bearing acid solution to prepare titanic acid particles is a crucial step for the production of TiO2 material. The hydrolysis which takes place in HCl medium was investigated particularly with the purpose of preparing coarse particles with narrow size distributions for applications such as Ti metal powder production. The key factors that affect the hydrolysis ratio and rate, the morphology, and the size of the titanic acid particles were investigated. The results illustrated that temperature, initial free acid and equivalent TiO2 concentrations cross-influence the above-mentioned key attributes of the product particles. Near spherical rutile particles with a D50 of around 30 mu m were obtained under the optimal parameters. Four stages, including incubation, acceleration, near steady-state reaction, and deceleration, were observed during the progress of the hydrolysis reaction, while the precipitate morphology evolved from irregular to smooth, and to round as a result of the nucleus agglomeration. (C) 2021 Elsevier B.V. All rights reserved