Usage of Rice Husk for the Production of Low-Temperature Cement: Physico-Chemical and Technological Aspects

Synthesis of metallic silicon by reaction of silica in rice hulls with aluminum and its hydrochlorination

The cement industry generally spends about 30-40% of production costs to provide energy for production. It forces the cement industry to look for cheaper and widely available alternative energy sources to increase its competitiveness. The dominance of fossil fuels poses another problem for the cement industry in the form of high CO2 emissions. To overcome this, PT Indocement Tunggal Prakarsa (ITP) Tbk, Palimanan Unit, is committed to continuously looking for alternative energy sources by utilizing rice husks in the suspension preheater unit. This study aims to evaluate the performance, especially the reduction of CO2 emissions and the economic benefits of energy substitution applications using rice husks. Based on the calculation in 2020, there will be an increase of 37% in 2021, and the total energy of rice husks will reach around 1,996,671 GJ. It is equivalent to using fossil fuel coal of approximately 106,450 tonnes. The contribution of rice husks to primary energy consumption seems to continue to increase yearly. A significant increase occurred between 2020 - 2021, and the contribution of rice husks reached 23%. Rice husks usage has reduced CO2 emissions by almost 220,000 tons of CO2e and brought production cost benefits to around 40 billion by 2021. Therefore, the substitution of coal fuel using rice husk has proven to be effective in reducing CO2 emissions in the cement production process. By still paying attention to the reliability of the process and the quality of the cement products produced, these efforts can be continuously encouraged to realize cement products that are more environmentally friendly.

Rice is regarded as one of the most valuable sources which is consumed by almost fifty percent of the world’s population. Rice husk ash is a by-product substance obtained from the rice husk by thermal and chemical treatment. The non-crystalline nature of silica content in rice husk, which is converted to crystalline silica such as quartz, tridymite, and cristobalite on thermal treatment. It has been an important material which impacts not only enhances the betterment of industrialization but also protects the environment from pollution. The produced silica was characterized by various analyses such as Fourier transform infrared spectroscopy (FTIR), X-ray diffraction analysis (XRD), Scanning electron microscope (SEM), Transmission electron microscope (TEM), and Thermal analysis. This review is given attention to integrating and investigating processing, properties, characterization, reactivity, and application of rice husk (RH) and rice husk silica (RHS).

Li4SiO4 pellets templated by rice husk for cyclic CO2 capture: Insight into the modification mechanism

Mullite synthesised for low cost processing can be produced by using waste powders from two Thai industrial sources; (i) aluminium oxide from a surface coating process, and (ii) silica from rice husks. Aluminium oxide obtained as a waste product powder was treated and calcined to give a specific BET surface area, 105 m 2 /g. SiO 2 was obtained from the treatment of rice husks. The silica from the treated rice husks is present as the amorphous phase and has a specific BET surface area of 291 m 2 /g. The resulting silica has a high purity, >99.0%. The treated aluminium oxide and the silica from the rice husk were mixed together in a ball mill, dried and pressed into pellet shaped compacts at various pressures, using conventional methods. The pellets were heated to maximum sintering temperatures in the range 1400-1700°C with different holding times; these varied for each of the maximum sintering temperatures. The density of the resulting sintered mullites was measured by Archimedes' method. The XRD profiles and SEM micrographs obtained showed only the pure mullite phase to be present when sintered to 1500°C for 1 hr. No other phases were apparent. The maximum relative density of the sintered mullite was found to be ∼98 %, a value obtained from the pellets sintered at 1700°C for 3 hr. The mullite ceramics were prepared for testing in 3 point bending strength and methods compared to commercial mullite materials. Mullite ceramics prepared from Sumitomo, A21, were mixed with silica from rice husk treated with HCl, and proprietary method have shown higher bending strength than materials prepared using powder from the aluminium surface coating mixed with rice husk silica treated with HCl and proprietary method. The mechanical properties have been correlated with the formation of a glassy phase formed around the mullite grains.

Cement production, a critical component in concrete manufacturing, is a significant contributor to air pollution. To address this environmental challenge, identifying sustainable alternatives for partial cement replacement is essential. Indonesia, a major rice-producing country, generates large quantities of rice husk waste and rice husk ash as by-products, which could serve as potential supplementary cementitious materials. This study investigates the feasibility of utilizing rice husk waste and rice husk ash as partial cement replacements in concrete mixtures. Cement was partially replaced with rice husk and rice husk ash at proportions of 9.5%, 10.5%, and 11.5%, with 1% superplasticizer added to each mix. The concrete compressive strength tests were conducted at 14 and 28 days, targeting a normal concrete strength of 25 MPa. The findings reveal that the mixture with 9.5% rice husk ash and 1% superplasticizer achieved the highest compressive strength, demonstrating the potential of these by-products in sustainable concrete production.

Concrete is one of the most widely used materials in the world, and its utilization is rising drastically with the increasing population. Around 5-8% of global carbon emissions are caused by cement production. On the other hand, approximately 160 million tons of rice husk, considered agrowaste, turn into ash annually. Rice husk ash (RHA) is particularly attractive due to its high silica content and great potential to be used as a cementitious material. However, impurities such as alkali metal oxides and uncontrolled combustion reduce the quality of silica and promote its crystallization. Numerous studies have focused on obtaining active silica through acid leaching to remove impurities, but the study on the reaction kinetics of functionalized rice husk ash is very limited. In this research, 0.1M hydrochloric acid (HCl) was used to leach rice husk at temperatures of 50°C, 60°C, and 70°C for 1.5 hours. The rice husk was then burned at 800°C for 2 hours. Subsequently, the ash was examined using various analytical and computational techniques to develop an in-depth understanding of the burning process, aimed at producing functionalized amorphous silica for sustainable construction. It was observed that 99.39% silica with 95.04% amorphous content was formed by treating rice husk with 0.1M HCl at 70°C for 1.5 hours, followed by combustion at 800°C for 2 hours. Furthermore, reaction kinetics parameters were identified using the Coats-Redfern kinetic model for the two different reaction zones of the burning process.

Rice Husk Ash (RHA) is a well-known supplementary cementitious materials (SCMs) that can be used for concrete with reduced CO2 contributions. In 2016, only Nepal produced 5.2 million tonnes rice that gave about 1.14 million tonnes rice husk. The rice husk can also be used directly in a cement kiln as a fuel. This study analysis the potential CO2 reductions from three scenarios and emphasis strengths, weaknesses, opportunities and treats in the production systems for initiate a decision process with possibilities to get an industry project financed from the green climate found. The highest CO2 benefits were from rice husk used in a cement kiln were half of the yearly rice husk production in Nepal could reduce the climate impact with 808000 tonnes CO2.

Production of rice husk in Central Java province is around 2,825,000 tonnes annually. It can be used as an alternative energy source to substitute coal in combustion during cement production. This study was conducted to determine the impact of rice husk as a substitute energy source in cement production. The observations of rice husk comprised calorimetric tests, physical and chemical tests, and percentage rice husk substitution for coal as firing energy. The chemical properties of the cement tested include the chemical content, MgO and SO3 contents, loss on ignition, insoluble residue, and total alkali. The results show that the chemical content of cement which is produced using rice husk as a substitute for coal in the combustion process still meets the Indonesian National Standard.

This study was conducted to evaluate the properties of cement bonded particleboard made from rice husk and sawdust. Sawdust and rice husk fine boards were made using two ratios of cement and particles of 70:30 and 80:20, but rice husk coarse was made with a ratio of cement and particle of 80:20. The density of sawdust and rice husk fine boards in a ratio of cement and particles of 70:30 was 960 and 880 kg/m3 respectively. If the cement ratio was increased to the ratio of 80:20, the density increased to 1140 and 1200 kg/m3 respectively. The density of rice husk coarse boards was 980 kg/m3. The MOR of boards made from saw dust and rice husk fine in a ratio of 70:30 was 5.36 and 2.48 N/mm2 respectively. It was 5.30 and 4.63 N/mm2 in a ratio of 80:20. The MOE of saw dust and rice husk fine boards in a ratio of 70:30 was 3302.96 and 1684.52 N/mm2, and in a ratio of 80:20 it was 3569.28 and 3139.27 N/mm2 respectively. The MOR and MOE for rice husk coarse boards were 6.08 and 3041.71 N/mm2 respectively. Rice husk fine and rice husk coarse board showed excellent properties in a ratio of cement and particles of 80:20. Therefore, rice husk can be an alternative source of raw material for manufacturing of cement bonded particleboard. DOI: http://dx.doi.org/10.3329/bjsir.v47i3.13060 Bangladesh J. Sci. Ind. Res. 47(3), 273-278, 2012

Powder metallurgy magnesium composite with magnesium silicide in using rice husk silica particles

Research on the determination of amorphous silica in Alor rice as an additive in the manufacture of portland composite cement has been carried out. The aim this to determine the concentration of amorphous silica in the form of oxides in rice husk ash with variations in time and combustion temperature. Washed rice husks are heated in an oven at 100 °C for 24 hours. After that rice husk is heated in the furnace with variations in temperature and time. Rice husk ash originating from the furnace combustion is then cooled for 24 hours and smoothed in a blender for 3 minutes, then sifted on the number size 230 sieve and analyzed using X-RD and X-RF. X-RD results showed that the rice husk ash samples were amorphous with the name Chitopentaose caprate (C200H363N5O38). While the results of X-RF at combustion with a temperature of 700 °C and time of 4 hours obtained amorphous silica at 97.50% with a very low CaO concentration of 0.467%.

Pursuing sustainable energy solutions has increased interest in utilizing agricultural waste for energy generation. Among these waste materials, rice husk stands out due to its abundance and potential as a renewable energy source. Gasification, a thermochemical process converting biomass into valuable synthesis gas (syngas), offers a promising pathway for harnessing the energy content of rice husk. This systematic review presents a comprehensive analysis of rice husk gasification, focusing on technology, performance, and sustainability aspects. Drawing from a wide range of literature sources, including research studies, technical reports, and advancements in gasification techniques, the review aims to provide a holistic understanding of the field. The review elucidates the different gasifier technologies used for rice husk gasification, discusses performance metrics evaluating gasification efficiency, gas composition, and energy yield, and examines the sustainability implications of the technology. It also analyzes the influence of rice husk characteristics on gasification outcomes and identifies trends, innovations, and persistent challenges within the domain. This review improves rice husk gasification research by categorizing and synthesizing. Researchers, politicians, and industry stakeholders looking to understand the technology's potential and limitations might benefit from its findings. This evaluation helps guide decision-making and promote rice husk gasification innovations as the globe transitions to sustainable energy.

A preliminary study of manufacture of cement from rice husk ash

Biomineralization, dissolution and cellular studies of silicate bioceramics prepared from eggshell and rice husk.