Pre-treatment of Ultramafic Nickel Ores for Improved Mineral Carbon Sequestration

Mineral carbon sequestration (MCS) is a type of carbon storage based on natural rock weathering processes where CO2, dissolved in rainwater, reacts with alkaline minerals to form solid carbonates. Although MCS has advantages over other carbon storage techniques, an economic MCS process has not yet been developed. Two approaches were taken in this work to reduce the cost of MCS. The first approach was to use a waste material, serpentine waste from ultramafic nickel ore processing, as a feedstock. The second approach was to use pre-treatments to increase the carbon storage capacity of the waste material. Two pre-treatments were developed in this work. The first pre-treatment, microwave pre-treatment, was identified as a way not only to improve the carbon sequestration capacity of the waste, but also to improve the mineral processing of ultramafic nickel ores. Microwave pre-treatment was shown to successfully convert serpentine in ultramafic nickel ores to olivine, to improve the grindability of ultramafic nickel ores with consistent texture, to reduce the viscosity of ultramafic nickel ore slurries by an average of 80%, and to enhance the CO2 storage capacity of ultramafic nickel ores by a factor of up to 5. The second pre-treatment developed was leaching with ligands at neutral to alkaline pH. Catechol, EDTA and tiron were shown to greatly improve the leaching rate and total magnesium leached from ultramafic nickel ores. While EDTA proved to be too strong of a ligand to allow the precipitation of MgCO3 from solution, catechol and tiron promoted the formation of MgCO3, particularly at pH 10. Overall, tiron was the most effective ligand for enhancing MCS and increased the CO2 storage capacity of ultramafic nickel ores by a factor of up to 3. Although the pre-treatment techniques developed required optimization, both microwave pre-treatment and leaching with ligands at neutral to alkaline pH show promise for ultimately reducing the cost of MCS

Hydration of dicalcium silicate and diffusion through neo-formed calcium-silicate-hydrates at weathered surfaces control the long-term leaching behaviour of basic oxygen furnace (BOF) steelmaking slag

Alkalinity generation and toxic trace metal (such as vanadium) leaching from basic oxygen furnace (BOF) steel slag particles must be properly understood and managed by pre-conditioning if beneficial reuse of slag is to be maximised. Water leaching under aerated conditions was investigated using fresh BOF slag at three different particle sizes (0.5–1.0, 2–5 and 10 × 10 × 20 mm blocks) and a 6-month pre-weathered block. There were several distinct leaching stages observed over time associated with different phases controlling the solution chemistry: (1) free-lime (CaO) dissolution (days 0–2); (2) dicalcium silicate (Ca₂SiO₄) dissolution (days 2–14) and (3) Ca–Si–H and CaCO₃ formation and subsequent dissolution (days 14–73). Experiments with the smallest size fraction resulted in the highest Ca, Si and V concentrations, highlighting the role of surface area in controlling initial leaching. After ~2 weeks, the solution Ca/Si ratio (0.7–0.9) evolved to equal those found within a Ca–Si–H phase that replaced dicalcium silicate and free-lime phases in a 30- to 150-μm altered surface region. V release was a two-stage process; initially, V was released by dicalcium silicate dissolution, but V also isomorphically substituted for Si into the neo-formed Ca–Si–H in the alteration zone. Therefore, on longer timescales, the release of V to solution was primarily controlled by considerably slower Ca–Si–H dissolution rates, which decreased the rate of V release by an order of magnitude. Overall, the results indicate that the BOF slag leaching mechanism evolves from a situation initially dominated by rapid hydration and dissolution of primary dicalcium silicate/free-lime phases, to a slow diffusion limited process controlled by the solubility of secondary Ca–Si–H and CaCO₃ phases that replace and cover more reactive primary slag phases at particle surfaces

Removal of non-CO2 greenhouse gases by large-scale atmospheric solar photocatalysis

Large-scale atmospheric removal of greenhouse gases (GHGs) including methane, nitrous oxide and ozone-depleting halocarbons could reduce global warming more quickly than atmospheric removal of CO2. Photocatalysis of methane oxidizes it to CO2, effectively reducing its global warming potential (GWP) by at least 90%. Nitrous oxide can be reduced to nitrogen and oxygen by photocatalysis; meanwhile halocarbons can be mineralized by red-ox photocatalytic reactions to acid halides and CO2. Photocatalysis avoids the need for capture and sequestration of these atmospheric components. Here review an unusual hybrid device combining photocatalysis with carbon-free electricity with no-intermittency based on the solar updraft chimney. Then we review experimental evidence regarding photocatalytic transformations of non-CO2 GHGs. We propose to combine TiO2-photocatalysis with solar chimney power plants (SCPPs) to cleanse the atmosphere of non-CO2 GHGs. Worldwide installation of 50,000 SCPPs, each of capacity 200 MW, would generate a cumulative 34 PWh of renewable electricity by 2050, taking into account construction time. These SCPPs equipped with photocatalyst would process 1 atmospheric volume each 14–16 years, reducing or stopping the atmospheric growth rate of the non-CO2 GHGs and progressively reducing their atmospheric concentrations. Removal of methane, as compared to other GHGs, has enhanced efficacy in reducing radiative forcing because it liberates more °OH radicals to accelerate the cleaning of the troposphere. The overall reduction in non-CO2 GHG concentration would help to limit global temperature rise. By physically linking greenhouse gas removal to renewable electricity generation, the hybrid concept would avoid the moral hazard associated with most other climate engineering proposals

LOYALTY PROGRAMS AS AN INSTRUMENT FOR CUSTOMER RELATIONSHIP MANAGEMENT

Ostatnie lata to okres, w którym programy lojalnościowe zyskały ogromną popularność, jako narzędzie budowania relacji z klientami. Pierwsze programy powstawały w Stanach Zjednoczonych w XIX wieku i od razu zyskały sympatię wśród klientów. W ciągu tak długiego okresu przeszyły głęboką ewolucję. Na początku zbierano znaczki, pieczątki lub kupony, a obecnie dzięki zaawansowanej technologii stosuje się systemy informatyczne do zarządzania programami lojalnościowymi. Przedsiębiorstwa wprowadzają programy lojalnościowe, które mają być zachętą do nabycia produktu lub usługi. Program lojalnościowy ma na celu budowanie długotrwałych relacji z klientem, gdzie oprócz zysku firmy, ważniejszą kwestą jest zdobycie zaufania oraz lojalności wśród klientów.Recent years have been a period in which loyalty programs have gained immense popularity as a tool for building relationships with customers. The first programs were created in the United States in the nineteenth century and immediately gained sympathy among customers. During such a long period pierced deep evolution. At the beginning collect stamps, stamps or coupons, and now thanks to the advanced technology systems used to manage loyalty programs. Enterprises implement loyalty programs that are to be encouraged to purchase a product or service. Loyalty program aims to build long-term relationships with customers, where in addition to the company's profit, about the question is more important to gain the trust and loyalty of customers

Continuous improvements in third year chemical engineering design

An impending retirement has led us to reevaluate the course: should we keep it - and if so who teaches it, or should we look to change it? The course was co-taught with a new faculty member, coupled with internal reviews and discussions. Ultimately, we decided to keep the course, and also to work to broaden its base. Historically, the design problems have been petrochemical in nature. Each team gets a reaction, with a first order rate law, as well as a production rate and fractional conversion. From this, they do the design calculations for a reactor and separator, and also generate the base engineering drawings. This past year, the project types were expanded to include environmental remediation and hydrometallurgical extraction. The environmental remediation problems involved wastewater processing (eg., BOD oxidation) which can be treated as a first order reaction. The hydrometallurgical problem (Li leaching from spodumene) also was set up as first order. Additionally, we provided the option of a case study review. The students chose a classic chemical safety incident, reviewed the details, and created a summary report which included recommendations on how to incorporate learnings from the incident into the curriculum.Both authors would like to acknowledge receipt of a TEAL Fellowship from the Faculty of Applied Science and Engineering, University of Toronto

CONTINUOUS IMPROVEMENTS IN THIRD YEAR CHEMICAL ENGINEERING DESIGN

An impending retirement has led us to reevaluate the course: should we keep it - and if so who teaches it, or should we look to change it? The course was co-taught with a new faculty member, coupled with internal reviews and discussions. Ultimately, we decided to keep the course, and also to work to broaden its base. &#x0D; Historically, the design problems have been petrochemical in nature. Each team gets a reaction, with a first order rate law, as well as a production rate and fractional conversion. From this, they do the design calculations for a reactor and separator, and also generate the base engineering drawings. &#x0D; This past year, the project types were expanded to include environmental remediation and hydrometallurgical extraction. The environmental remediation problems involved wastewater processing (eg., BOD oxidation) which can be treated as a first order reaction.  The hydrometallurgical problem (Li leaching from spodumene) also was set up as first order.  Additionally, we provided the option of a case study review. The students chose a classic chemical safety incident, reviewed the details, and created a summary report which included recommendations on how to incorporate learnings from the incident into the curriculum.&#x0D;  </jats:p