Mt Of Material Research Articles

Mapping material use and embodied carbon in UK construction

The latest available high-level top-down analysis shows that the embodied carbon of the UK construction in 2018 was 43 MtCO2e, of which 80% came from materials and on-site activities. In this paper, for the first time, we combine a detailed bottom-up model of representative residential and non-residential buildings with top-down infrastructure and other material consumption data to quantify the material use and embodied carbon in UK construction. We found that almost 100 Mt of materials were used with an embodied carbon of 25 Mt CO2e. Half of these emissions were from concrete. We found that existing top-down approaches underestimate emissions by up to 20%. We developed a benchmark for UK building typologies and explore interventions to achieve the UK's carbon reduction goals. We found that conversion from non-domestic to domestic purposes can bring 34% embodied carbon savings of the construction total, 30% by avoiding demolition, 20% by switching to the most material and carbon efficient technology options and by 10% if all new houses were multi-storey buildings. We have shown that the bottom-up approach allows identifying areas with high potential for decarbionisation. Due to the flexibility of the model, it can be successfully used in other countries and regions.

Life-of-mine optimization for integrated open stope development and production scheduling using a mixed-integer linear programming framework

ABSTRACT Extraction and development sequences must be scheduled strategically in order to maximize the life of mine. The complexities and computational difficulties associated with underground mine planning makes it challenging and open to further research. This paper presents a mathematical programming framework based on mixed-integer linear programming (MILP) formulation for integrated open stope development and production scheduling. Additionally, the MILP model incorporates backfilling, operational levels control, and stope extraction duration control during production scheduling. The MILP model generated a net present value of $244.7 M and determined the capital, ventilation, operational, and ore pass development schedules as well as mining and processing schedules for a gold project with 25 years mine life. A total of 2.48 Mt of material was extracted and processed out of 2.88 Mt mineralized material.

Towards an eco-efficient ready mix-concrete industry: Advances and opportunities. A study of the Metropolitan Region of Buenos Aires

There is a growing demand in Latin America and the Caribbean for building materials to satisfy the need for adequate housing and infrastructure in urban areas. This paper examines the consumption of materials and environmental impact of ready-mix concrete produced in the Metropolitan Region of Buenos Aires in a certain period of time. Material flow analysis and life cycle assessment (LCA) were performed. The average composition concrete was estimated by means of surveys conducted with ready-mix concrete producers. The material efficiency (ME), CO2 equivalent emissions (ECO2eq), materials and energy use were used as environmental indicators. Feasible impact reduction strategies and their influence on the LCA were also explored. 7.16 Mt of materials were required to produce 2,604,862 m3 of ready-mix concrete, within 99.1% corresponded to raw materials, while 0.9% corresponded to secondary raw materials. 5.36 Mt (∼78.6%) of the extracted materials belong to aggregate production and they represent ∼19.5% of the ECO2eq. Portland cement is the largest contributor to ECO2eq and the constituent material with the lowest ME. Using recycled aggregates is the strategy that contributes the most to the reduction of the use of raw materials (∼8.9% lower use of raw material by using 20% recycled coarse aggregate), while replacing Portland cement with supplementary cementitious materials (SCM) is the one that reduce the most the ECO2eq (the use of Portland cement without SCM would increase ECO2eq by ∼13.6%). This research provides a novel approach that quantifies the effect of modifying the concrete mix and replacing raw materials by secondary raw materials, bringing a new understanding to the sustainability of building materials.

The UK industrial decarbonisation strategy revisited

Since 2010, successive UK governments have produced various strategies for industry to reduce carbon dioxide emissions (‘decarbonise’). This paper scrutinises the most recent version that was published in March 2021: the Industrial Decarbonisation Strategy (IDS). It contrasts the policy content of the IDS with previous industrial roadmaps, action plans and strategies (including the Clean Growth Strategy of 2017). In addition, it compares the proposals in the IDS with the latest recommendations of the UK government's independent Climate Change Committee, as well as drawing on lessons learned from the techno-economic assessments published by the author and his collaborators for a number of key ‘foundation industries’. The latter emit significant shares of UK industrial carbon dioxide (CO2) emissions: the iron and steel (∼25%), chemicals (∼19%), cement (∼8%), pulp and paper (∼6%) and glass (∼3%) sectors. They also produce about 28 Mt of materials per year, which are worth £52 billion to the UK economy, and account for ∼10% of UK total carbon dioxide emissions.

Estimating the construction material stocks in two Canadian cities: A case study of Kitchener and Waterloo

Growing worldwide population and expansion in urban land area are becoming global concerns. As a result of this growth, material consumption in cities is increasing to adapt with the needs and activities of the urban populations. Among the materials consumed, construction materials are responsible for the greatest share of material use in cities. To plan for the future demands of the urban population, policymakers should gain insight regarding current and future material use. Material stock accounting is a tool that can be used to provide an understanding of the historical material use in cities and the consumption patterns. In this research a bottom-up material stock accounting approach is used to estimate the quantity of construction materials embedded in the building, road and sidewalk stocks in Kitchener and Waterloo. These cities are located in the Region of Waterloo, one of the fastest growing urban areas and the tech-hub in Canada. In order to make these estimations, existing stocks from the early 1900s are considered and a growth pattern is presented from 2003 to 2018 using the existing data, and projected up until 2041. The results show that in 2018, there were around 65 Mt of materials in this area, which is a 23% growth from 2003. The per capita material consumption has also increased from 155 t/cap to 164 t/cap over this 15-year period. At the same time, building demolitions resulted in 2.572 Mt of construction materials turning into waste during this time period. Moreover, it is estimated that by 2041 an additional 12 Mt of materials will be added to the building, road, and sidewalk stocks of Kitchener and Waterloo. The results of this study will help cities take effective steps toward achieving circular economy and plan for implementing urban mining strategies.

Pilot-Scale Continuous Conveyor Diffusion Extraction System for Sweet Sorghum

The purpose of this paper is to present preliminary results from testing a pilot-scale sweet sorghum diffusion extractor that was designed to extract the juice from sweet sorghum stalks while simultaneously filtrating the extracted juice. The ultimate use of the juice is fuel grade ethanol. In essence, the system is a large coffee percolator that works by running shredded sorghum through a conveyor with recirculating hot water running over the crop to extract the sugar through diffusion. The current system spans 10 m in length, is 1m wide, and 0.6 m high. The sorghum is harvested with a forage chopper, and discharged at a constant rate into the trough. The sorghum moves at a rate of 0.2 m per minute, so the sorghum is in the diffusion system for 20 minutes. The water/juice is sprayed over the chopped stalks and is kept at a target temperature of 660C. A roller fixture located at the end of the trough helps squeeze out some of the remaining juice. The pilot scale sweet sorghum diffusion system continuously extracts the sugar at a rate of 3 metric tons (mt) of sorghum an hour with a minimum sugar extraction of 60%. During our pilot testing phase we were able to process 0.65 mt of material per hour with a resultant brix of 6%. The system was halted several times to adjust the heating system, so we are confident that with further testing we can process at least 3 mt per hour of material. The conversion from the conventional harvesting and roller press of the sorghum stalk to this method could resulted in a 66% reduction in energy to harvest and extract the juice.

Cia Minera Los Pelambres: a project history

Abstract The first documented discovery of copper mineralization at Los Pelambres was by William Braden, the American geologist, who noted and explored the area in 1920. He drove a series of short adits into the canyon wall, but these did not penetrate beyond the leached cap of the deposit. After the work of Braden, there was no further activity until 1955 when two Chilean companies, Minera Protectora and Minera Los Pelambres, staked claims in the area. The Protectora and Los Pelambres claims were surveyed in 1960 and 1970 respectively. The United Nations first became involved in 1964 with a surface examination of the property. This was followed by a further examination by the Chilean Institute of Geological Investigation financed by Corfo (a Chilean government organization) in 1967 and 1968. Beginning in 1969, a partnership arrangement between the United Nations and Enami (the Chilean government organization dedicated to small-scale mining) undertook serious exploration of the property including diamond drilling programmes. This work developed a combined probable and possible ore reserve of 428 Mt of material with a grade of 0.78% copper and 0.033% molybdenum. The drilling was confined largely to the valley bottom. This work was finished in 1971. In 1978 an international licitation for bids on the claims prompted examination by Anaconda geologists. Anaconda (then a subsidiary of Atlantic Richfield) was successful in the bidding and in 1983 they produced a study which examined the alternative means of exploiting the deposit. The conclusion of this study was that it was technically feasible to mine the deposit as an open pit operation at a scale of 60 000 tpd using conventional froth flotation techniques to recover the copper minerals. The study took three and a half years to complete at a cost of $59 M. The study, however, concluded that although the project could produce a satisfactory rate of return, the project economics were marginal in the light of the copper prices projected at that time. In this study the ‘geological reserves’ were stated to be in excess of 3 Gt at a grade of 0.62% copper. Shortly thereafter Atlantic Richfield made a strategic decision to divest itself of all its mining assets and in 1986 Anaconda Chile was acquired by the Luksic Group. Montagu Mining Finance (MMF) were appointed, to advise the Luksic group, in late 1987. It was MMF’s view that the opportunity might exist to finance the project using a debt for equity swap under Chile’s Chapter XIX rules. At that date the largest debt swap, in the mining industry, that had been completed in Chile was for $35 M and it was MMF’s view that the Chilean central bank would not countenance a swap much larger than this. MMF decided therefore to examine developing the project with a capital budget limited to what might be achievable through a debt swap, and in early 1988 consultants were appointed to examine the feasibility of mining the deposit on a small scale. As part of their brief, the consultants examined the distribution of copper throughout the deposit and concluded that there exist two high grade zones, the East Zone and the West Zone, which together contain 40 Mt at an average grade of 1.52% copper. It is these higher grade zones that have been the target for initial mining and at present the mine is being operated as a 5000 tpd underground operation. Initial operation and addition drilling on the East Zone has confirmed the feasibility study estimates. However, a further high grade zone, The Central Zone, has now been confirmed by drilling and trial mining and a study has indicated the potential for an increase in production to 15 000 tpd by mining the West and Central Zones by open pit methods.