Showing papers on "Co-processing published in 2023"

Alternative Fuels Substitution in Cement Industries for Improved Energy Efficiency and Sustainability

Abstract: The conventional energy source in cement industries is fossil fuels, mainly coal, which has a high environmental footprint. On average, energy expenditures account for 40% of the overall production costs per ton of cement. Reducing both the environmental impact and economic expenditure involves incorporating alternative energy sources (fuels) such as biomass, solid-derived fuel (SDF), refuse-derived fuel (RDF) etc. However, within cement plants, the substitution of conventional fossil fuels with alternative fuels poses several challenges due to the difficulty in incorporating additional fuel-saving techniques. Typically, an additional 3000 MJ of electricity per ton of clinker is required. One of the most effective solutions to this is thermal optimization through co-processing and pre-processing, which makes it possible to implement additional fossil-fuel-saving techniques. In developing nations such as Togo, waste-management systems rely on co-processing in cement factories through a waste-to-energy relationship. Also, there are some old cement plants with low-efficiency, multi-stage preheaters without pre-calciners, reciprocating huge coolers, low-efficiency motors etc., which still operate and need to be made environmentally sustainable. However, compared to modern kilns which can have up to 95% of energy recovery from waste, an old suspension preheater kiln can recover only up to 60% of its heat energy depending on the cooler type, and due to the lack of a bypass and combustion chamber (pre-calciner). This research paper evaluated the performance of a cement plant incorporating AF and presents the procedures and recommendations to optimize AF substitution in cement plants. To achieve this, a comparative performance study was carried out by assessing the alternative fuel characteristics and the equipment performance before and after the incorporation of the alternative fuel. Data were collected on the optimum substitution ratio, pre-processing and co-processing performance, raw-meal design and economic analysis. Results indicated that the cost to be covered per ton of waste input is €10.9 for solid-derived fuel (SDF), €15 for refuse-derived fuel (RDF), and that the co-processing cost optimization for the cement plant could have a cost saving of up to 7.81€/GJ. In conclusion, it is recommended that appropriate kiln and alternative-fuel models be created for forecasting production based on various AF.

The possibility of using silicate-containing waste in the production of building materials

Abstract: The solution to the problem of reducing the resource intensity of the construction industry is possible due to the involvement of large-tonnage waste in the production of building materials as a feedstock. Despite the fact that this task has been standing for a long time, the share of waste in raw materials for the production of building materials is still not large today. The article presents the results of research on the properties of concrete mixtures for self-leveling floors based on silicate-containing waste. In the course of experimental studies, the compositions of raw mixtures containing Portland cement, finely ground broken glass, concrete scrap, and liquid glass were optimized. The ratio of the composition of concrete mixes with the use of waste was revealed, at which the quality of the finished product is maintained. Keywords: cullet, concrete scrap, liquid glass, liquid glass, concrete mixtures.

Review on the use of sludge in cement kilns: mechanism, technical, and environmental evaluation

Abstract: With the increasing sludge production and cement carbon emissions worldwide, there is an urgent need to develop synergistic approaches to sludge co-process in cement kilns options for building up an interactive sludge carbon reduction process. Cement kilns with temperatures as high as 1450 °C can dissipate various wastes and completely decompose or solidify harmful substances, including dioxins and heavy metals, in the cement crystal structure. Therefore, cooperative cement kiln disposal of sludge can thoroughly decompose organic components as well as their intrinsically cured heavy metals. The vast majority of cement production lines in the world are already equipped for co-process, but the disposal of sludge is blended at a relatively small amount of about 6%. This paper first summarizes the physicochemical characteristics of different types of sludge. In addition, the discussion focuses on the sludge raw material substitution principle and the heavy metal solidification process. The mechanism of K+, Na+, and Cl- plasma damage is further investigated in depth. The overview study predicts the annual carbon emission reduction content of about 25 million tons from two routes of cement kiln co-process of sludge and other solid wastes such as raw material substitution and alternative fuels and cross industries.

"industrial waste utilization in the production of building materials on ecostroinii-pv llp example "

Abstract: "The results of the work of EcostroyNII-PV LLP on the processing of technogenic waste of energy and metallurgy of the Republic of Kazakhstan, Pavlodar region are presented. The use of waste in the manufacture of construction products is one of the most effective solutions to environmental problems in the region. The proposed technology for the production of construction products using ash and slag waste provides for innovative compositions of raw materials mixtures and provides an increase in operational characteristics and an increase in labor productivity in construction. The applied technology, in comparison with existing analogues, provides for the use of local waste (ash and slag waste from the burning of Ekibastuz coal, bauxite sludge of the Pavlodar aluminum plant, steelmaking slag). They differ in chemical and granulometric composition, as well as binding properties from other analogues and prototypes. In the production of construction products, a concrete mixture has been introduced and patented, including, %: slag-Portland cement – 14.32–17.00; sand – 18.74–25.52, crushed stone – 46.50-49.71, alumina sludge obtained during processing of Kazakhstan bauxite – 5–7; self–disintegrating slag of steelmaking production – 5–7; ash and slag waste of thermal power plants from burning Ekibastuz coals – 5–7. According to the test results, the average tensile strength of building products (paving slabs, curbstones, hollow bricks) is 3.2 – 3.8 MPa (strength class 2.5). "

Co-Processing Biomass With Fossil Fuels

Abstract: Co-processing biomass with fossil fuels is considered as a promising technology to meeting the increasing energy demands while reducing the consumption of fossil fuels and the negative impacts to the environment. Drop-in biofuels that are potential replacement to petroleum fuels are essential to emission reduction in transportation and energy sectors. Biocrudes produced from thermochemical conversion are not applicable for direct implementation. Co-processing biocrudes with petrocrudes using existing refining infrastructure is an economic and ready-to-use option to help refineries decarbonize and advance biofuels production. Intensive efforts have been employed on co-processing through flexible fluid catalytic cracking (FCC) operations and demonstrated that the FCC units are able to tolerate biocrudes. Moreover, pioneering studies indicate that co-hydroprocessing is likely to be an option at the refinery plants. More work is needed to optimize FCC and determine the application of co-hydroprocessing.

Production of cement and its environmental impact

Abstract: This chapter deals with cement manufacture, cement properties, types of cements, blended cements and life cycle assessment of different types of cements. Cement is one of the most important building materials around the globe. It is used mainly as binding and strength giving medium for the production of concrete. It is estimated that global cement production reached 4.1 giga-tons in 2019, with China producing the large share. Because of the importance of cement as a construction material as well as the abundant availability of raw materials (limestone + clay), cement is produced in almost all the countries in the world. Cement production is a highly energy intensive process and the energy consumption of cement industry is nearly 5% of the total global industrial energy consumption. The theoretical energy consumption for producing 1 kg of Portland clinker is about 1.76 Mega joules. The kiln is the major energy consumer in cement making, while most electricity is consumed in the grinding of raw materials and clinker, to produce cement. Coal and natural gas are mainly used as fuel for calcining the raw materials in the kiln, it takes about 200 kg of coal to produce one ton of cement. Due to calcination, calcium carbonate in the kiln converts to calcium oxide and carbon dioxide and CO2 emissions contributed by fuel and raw meal combustion together with very small amount of CO2 emissions contributed by consumption of electricity (assuming that electricity is generated from fossil fuels), is the major CO2 emission source from cement production. It has been estimated that about 0.65–0.92 tons of CO2 are emitted from 1 ton of cement production, based on cement plant with modern technology and depending upon the ratio of clinker to cement.

Incorporation and solidification mechanism of manganese doped cement clinker

Abstract: Using municipal and industrial solid waste as a substitute raw material and fuel in cement rotary kiln co-processing is considered an economic and environmentally friendly alternative to the use of traditional fuels. However, the presence of heavy metals in solid waste is a growing concern in the cement rotary kiln co-processing technique. The solidification mechanism of heavy metals in cement clinker is directly related to their stabilization. Cement clinkers doped with manganese oxide (MnO2: 0.0%–5.0% wt%) were prepared in a laboratory to investigate the impacts of extrinsic Mn on cement clinker calcination. The insignificant changes in X-ray diffractometer patterns indicated that the fixed Mn had little influence on the mineral lattice structure. Raman spectra and X-ray photoelectron spectroscopy revealed the transformation of the silicate phase when the Mn dose was increased. Moreover, the satisfactory solidification ratio confirmed the incorporation of Mn in the cement clinker. These results provided evidence of the influence rule of Mn in the cement clinker calcination process. Furthermore, Raman spectroscopy showed great potential for the qualitative and semi-quantitative analysis of the cementitious materials derived from cement rotary kiln co-processing. These results will be important for the further development of green cement manufacturing technology.

Use of industrial waste for value-added products

Abstract: The world has been consuming a lot of natural resources as raw materials for industrial purposes and production. Globally, research is currently underway on how these natural materials will be able to satisfy the needs in the various industries with industrial waste to make processes cheaper and sustainable. The growing world population has created a great demand for growth in production industries. As production increases, it generates industrial waste, and how to dispose of the same is a very big question. Today, everyone is thinking about how many low-cost homes and infrastructure can be built. What materials and technologies can be used? Value-added products from industrial waste are becoming more and more popular in various parts of the world. Industrial production is considered as one of the sources of environmental pollution in the world. A lot of environmental burden is generated on Earth, which causes an increase in the carbon footprint due to the use of cement, sand, and crushed aggregates. This large quantity of waste generated causes problems of disposal along with the environmental degradation. These wastes are being used in construction industries. Waste from thermal power plants, aluminum refineries, and industries of fertilizers, iron, and plastics are used for manufacturing value-added products. If these wastes are used in various composites and other techniques, it will not only save a lot of natural resources but also will cause less environmental damage and reduce the carbon footprint. This chapter discusses the utilization of various industrial wastes for manufacturing value-added products for various purposes. This will optimize the cost of construction and various products as well as mitigate the waste disposal problem.

A preliminary study of mechanical treatments’ effect on the reactivation of hydrated cement paste

Abstract: More than 4.4 billion metric tons of cement were produced in 2021 [1], making it one of the most common building materials. Unfortunately, excessive cement use brings up several environmental concerns, one being the enormous volumes of CO2e (carbon dioxide equivalent) created as a by-product. CO2e is a standard unit for measuring carbon footprint and can be calculated for all greenhouse gases using global warming potential. Reducing CO2 and other greenhouse gas emissions is crucial in modern cement manufacturing, as 0.9 kg of CO2e is produced for every kg of cement. Cement manufacturing contributed by releasing 3.96 Gt of CO2e into the atmosphere in 2021. This issue is often remedied using recycled materials in the fresh concrete mix as supplementary or pozzolanic additives. Some researchers have focused on regaining the activity of hydrated cement paste by grinding and thermally activating it [2–5], but a low-strength binder would also work for many applications. A low-strength binder recovered with as little energy as possible (only grinding, no heat treatment) could be considered a more sustainable and less energy-intensive way of recovery of the cement binder matrix. This study investigated a technique for recycling hydrated cement paste by mechanical treatment to disintegrate the hydrated cement conglomerate to reveal the unhydrated cement particles [6] that can be used as a recovered cementitious binder from processing waste from the production of wood-cement boards. Processing waste is defined as cement particles containing hydrated and unhydrated cement [7] and spruce wood fibres. The partly hydrated cement in the waste stream was mechanically processed in a planetary mill to reactivate it and restore its cementitious characteristics. The binder was characterized by density and mechanical compressive strength.