White Mud Research Articles

Elastic modulus, water stability and resistivity for loess solidified with white mud based solid waste cementing material: Mechanism analysis and relationship establishment

To increase the engineering application value of white mud based solid waste cementing materials: white mud-slag and white mud-slag-Calcium Carbide Residue (CCR), this paper explored the changes in elastic modulus, water stability and resistivity of loess solidified with white mud based solid waste cementing material. Furthermore, relationships between elastic modulus, water stability and resistivity were established. The following conclusions can be obtained: The alkaline activation effect of CCR was stronger than white mud, therefore the formation rate of C-S-H and C-A-(S)-H cementitious products in CCR-containing solidified loess was more faster than that without CCR. At the same time, white mud not only served as an alkaline activator, but its finer CaCO3 components also helped fill pores, while the irregular fine particles provided nucleation sites for the formation of cementitious products. Consequently, slag-white mud-CCR solidified loess exhibited the best performance in terms of elastic modulus and water stability coefficient. This was followed by slag-white mud solidified loess and lime solidified loess. In addition, the analysis of the relationship between the resistivity of solidified loess and factors such as curing age, dry density, water content, elastic modulus, and water stability coefficient revealed that the main reasons for the increased resistivity of solidified loess were the consumption of internal water and the increase in cementitious products with poor conductivity. Furthermore, the modified resistivity formula was applied to establish the fitting relationships between the resistivity of solidified loess and various parameters. The formula has been successfully applied in the slag-white mud-CCR solidified loess, where the fitting of resistivity with various parameters yielded an R2 of 0.94. This paper facilitates the resistivity method (non-destructive testing) of loess treated with slag, white mud, CCR and promotes the application of these curing agents, contributing to their broader adoption in geotechnical engineering.

Structure and chemical composition of low-silicon white mud based on technology of black liquor combustion desilication

Structure and chemical composition of low-silicon white mud based on technology of black liquor combustion desilication

Effect of white mud on carbonation resistance of alkali activated slag

White mud (WM) is a solid waste produced in the process of papermaking and it remains to be effectively utilized. It contains a large amount of CaCO3 and residual alkali metal ions. This paper aims to explore the effect of WM on carbonation resistance of alkali activated slag. The changes in mechanical properties and microstructure of alkali activated white mud/slag (AAWS) after natural carbonation and accelerated carbonation were analyzed. The results indicate that the mechanisms of natural carbonation and accelerated carbonation are different. The carbonation depth achieved in 90 days of natural carbonation can be reached in just 14 days of accelerated carbonation. Samples with 15 wt% WM blended possesses the smallest carbonation depth and the highest compressive strength. WM can effectively mitigate the natural carbonation of AAWS by dissolving Mg2+ and Ca2+. Mg2+ can migrate to increase the solubility of calcite, promote the generation of hydrotalcite to absorb carbon dioxide, and reduce the carbonation degree. Ca2+ will migrate after the carbonation and decalcification of the gel product and reduce the decalcification sensitivity. This study offers a sustainable approach for improving the carbonation resistance of AAWS.

Carbon emissions assessment of cement mixing piles for soft loess improvement and carbon emission reduction using white mud-cement composite material

During the highway construction in the soft loess region of Northwestern China, there are always tens of thousands of cement mixing piles were used. Which generates a large amount of carbon emissions, thereby affecting the environment. The Simplified Energy and Emissions Assessment Model (SEEAM) is used to quantify carbon emissions considering monitoring data of IoT (Internet-of-Things) system. To reduce the error of the carbon emissions of large samples, Monte Carlo simulation was used to quantify carbon emissions based on the small samples. The results showed that cement had a 47,530.78 t carbon missions contributing the 95.64 % of the total carbon emissions. To concurrently ensure strength and reduce carbon emissions, this study investigates the unconfined compressive strength variations in white mud-cement composite material solidified soft loess. It indicated that 10 % and 20 % white mud provided an alkaline environment and nucleation sites for cement hydration reactions, combining the filling voids. According to the observation results of TG and SEM, the content of 10 % white mud increased the quantity of early hydration product CSH in cement. Which maintained a high level of strength by comparing the cement solidified soft loess. In addition, when the white mud content is 50 %, the white mud-cement composite material reduced 576 % carbon emissions in the cement mixing pile engineering. This study can provide guidance for the selection of engineering construction design schemes, as low-carbon emission schemes are conducive to green and sustainable development of the environment.

Study on characteristics of ammonia alkali white mud and mechanical properties of preparation of fluid solidified soil

Study on characteristics of ammonia alkali white mud and mechanical properties of preparation of fluid solidified soil

Analysis of compressive strength, durability properties, and micromechanisms of solidified loess using industrial solid waste: Slag–white mud–calcium carbide residue

Traditional lime-solidified loess presents the issue of high carbon dioxide emissions. This paper presents the development of a kind of cementitious material using industrial solid waste: slag–white mud–CCR (calcium carbide residue). The slag mainly contains CaO, SiO2, and Al2O3, with a 10.6 pH value. The white mud and CCR mainly contain CaCO3 and Ca(OH)2, respectively. We further assessed the efficacy of slag–white mud–CCR in solidified loess and employed SEM and TG/DTG to explore their micromechanisms. The pH value of the CB4 sample (slag–white mud–CCR with the lowest CCR content) was 42.3 % higher than that of pure loess. Considering the 3-day and 28-day compressive strength and the material costs, the optimal mortar mixture ratio was found to be slag–white mud–CCR = 60:32:8, and this mixture was used to solidify loess. The unconfined compressive strength of 15 % slag–white mud–CCR-solidified loess is almost 5.0 times and 6.0 times higher than that of lime-solidified loess at 7 and 28 days of curing age, respectively. The durability of the solidified loess after freeze–thaw and wet–dry cycles was significantly improved compared with that of lime- or slag-solidified loess. Specifically, 10 % and 15 % slag–white mud–CCR-solidified loess maintained a high compressive strength after eight freeze–thaw and wet–dry cycles. SEM and TG/DTG analyses of the mortar and solidified loess confirmed the formation of hydration products of C–S–H- and C-A-(S)–H-type gels. The compressive strength results were obtained using a dual mechanism: the cementation of loess particles through the formation of hydration products and their subsequent filling action.

Upcycling Textile White Mud to Fabricate MIL-125-Derived Amorphous TiO2@C: Effective Electrocatalyst for Cathodic Reduction of Antibiotics

Upcycling Textile White Mud to Fabricate MIL-125-Derived Amorphous TiO2@C: Effective Electrocatalyst for Cathodic Reduction of Antibiotics

A new disposal method for white mud: Replacing limestone in iron ore sintering

The pulp production process generates a CaCO3-rich solid waste known as white mud (WM), and its improper disposal is a cause for global concern. The present study investigates the composition, microstructure, and thermal decomposition characteristics of WM and proposes a strategy for replacing limestone with WM for iron ore sintering. Granulation and sinter pot tests were performed to evaluate the influence of added WM on the granulation and sintering processes. We assess the feasibility of using WM as a flux and discuss the mechanism through which WM affects the mineral phase and strength of the sinter based on metallographic and micropore observations. The results indicate that the sintering rate remains stable after replacing 50% of the limestone with WM via moisture control, and the quality and production indicators of the sinter do not change. Moreover, the mineral phase and microporosity remain similar to the basic case without WM, and the comprehensive index decreased by only 5.5%. Overall, this study demonstrates that it is feasible to replace 50% of limestone with WM in industrial sintering plants, which could significantly increase our WM disposal capacity and bring additional economic benefits.

Effect of white mud on properties of alkali activated slag

White mud is a solid waste from the papermaking industry, composed mainly of CaCO3 and residual alkali metal ions (such as Na+, Mg2+). In the current study, the feasibility of using white mud as partial replacement of slag in alkali activated materials is explored. The fluidity, setting time, autogenous shrinkage, mechanical properties, hydration products and microstructure of alkali activated slag containing different amount of white mud are studied. The results show that adding white mud reduces the fluidity of freshly mixed paste, setting time and autogenous shrinkage. The ions released from the white mud participate in the polymerization reaction, accelerate the hydration reaction in the early stage, and promotes the precipitation of Mg-Al and the formation of hydrotalcite. However, excessive quantities of white mud (above 15% of the binder) leads to the reduction of compressive strength. As the content of white mud is enhanced, the Ca/(Si + Al) ratio of the gel increases and the degree of polymerization is reduced. It has been shown that white mud has potential reactivity and can partially replace slag to prepare new alkali activated materials.

Ca3B2O6-modified papermaking white mud for CaCO3/CaO thermochemical energy storage

CaCO3/CaO thermochemical energy storage based on concentrated solar power plant is a promising technology because of its high working temperature and energy storage capacity. Papermaking white mud (PWM) from paper mill is a potential CaO-based precursor due to its high content of CaCO3. Herein, a novel Ca3B2O6-modified PWM was synthesized to examine its thermochemical energy storage performance. The influences of the types and dopant amounts of B2O3 precursors on the energy storage capacity of Ca3B2O6-modified PWM were discussed. The stable Ca3B2O6-modified PWM with the mass ratio of CaO to Ca3B2O6 = 88:12 exhibits superior energy storage performance and heat transfer property during CaCO3/CaO cycles. The effective conversion and energy storage capacity of Ca3B2O6-modified PWM are approximately 0.67 and 2129.6 kJ/kg at 31st cycle, respectively, which are 2.48 and 1.76 times as high as those of PWM and pure CaCO3, respectively. The introduction of Ca3B2O6 improves the sintering resistance and thermal conductivity of PWM, resulting in higher cyclic stability and lower decomposition temperature of CaCO3. Ca3B2O6 enhances the basicity and improves the strong basic sites of PWM, which is beneficial for the adsorption of CO2, leading to greater CO2 adsorption capacity. Moreover, Ca3B2O6 increases the oxygen vacancy concentration of PWM, which is conducive to the diffusion of O2– and production of CO32–, further improving energy storage capacity. Hence, Ca3B2O6-modified PWM seems to be a suitable energy storage material for the CaCO3/CaO process.

Green liquor desilication via black liquor combustion process for bamboo pulping

The presence of silicon in non-wood raw materials is known to interfere with the causticization of green liquor and the calcination of white mud, which has provided motivation for advances in alkali recovery technology. Therefore, reducing the silicon content of green liquor is the fundamental way to solve the problem. However, there are certain defects in conventional green liquor desilication, so this study provides a basis for desilication from green liquor via black liquor combustion and studies the desilication effect of a compound desilication agent on bamboo pulping black liquor. The results show that the desilication effect was better and the desilication rate could reach 84% when the Mg/Al proportion in compound desilication agent was 1:0.6. Meanwhile, the content of residual aluminum in green liquor decreased, which can avoid the influence of residual desilication agent on subsequent stages. Scanning electron microscopic images show that green-liquor-silicon-insoluble (GLSI) substance is a granular precipitate, and the X-ray diffraction analysis shows that GLSI substance has a complex structure similar to 3Al2O3•2SiO2•MgO. This implies that the desilication mechanism consists of chemical precipitation and physical adsorption.

Multifactor Analysis of Landslide Mechanisms: A Case Study of Yongji Expressway, China

Based on deformation monitoring and stability results obtained from geological mapping, geological drilling, macrolaboratory, and microlaboratory tests, the sliding mechanism of landslide in Guzhang County of Yongji expressway was studied. The bedding slope landslide results from cutting slope along the central white mud clay slip, and by on-site investigation and deep displacement monitoring, the clay is determined as the landslide surface. Combining the experimental results and similar geotechnical engineering experience, by back-calculation, the parameters of the soft interlayer are calculated as C (5 kPa) and ϕ (8.5°). Based on X-ray diffraction (XRD) and X-ray fluorescence spectroscopy (XRF) test, the results are concluded that the chlorite in clay interlayer is easily water softened, excavation slope after long-term heavy rainfall chlorite clay interlayer softening. Sustained rainfall and underground water levels showed a positive correlation when the slope is sliding, and the heavy rainfall continued to accelerate slope sliding. Furthermore, the slope surface displacement and profound displacement increase quickly, and rainfall and slope displacement also showed a positive correlation.

Green Conversion of Coal Fly Ash into Soil Conditioner: Technological Principle and Process Development

White mud is residue discharged during the acid method in the aluminum extraction process from coal fly ash, and this material is harmful to the environment. The implementation of an environmentally friendly and valuable way to use white mud is a key factor restricting the commercial application of the acid method in the fly ash alumina extraction technology. An analysis of white mud revealed the following: (1) it was highly enriched in SiO2 (70–80%) while concentrations of acid-soluble elements, such as Na, Al, and Fe, and some hazardous heavy metals, including Pb and Cr, were significantly lower than raw fly ash; (2) approximately 80% of SiO2 had relatively high reaction activity because of the foregoing Al-extraction treatment. Through an ingenious green chemical process, the complete conversion of white mud into silicon–calcium fertilizer (SCF) was achieved under very mild reaction conditions (approximately 100 °C and atmospheric pressure). Waste liquor was totally recycled, and no secondary solid waste was generated. The SCF had an available silicon content (ASC) of 35%, significantly higher than the commercial standard (20%). Converting them into soil conditioners or ecological remediation materials with the lowest possible energy consumption and secondary pollution may be the most promising approach for the future disposal of aluminosilicate industrial solid wastes.

The use of red mud and kaolin waste in the production of a new building material: Pozzolanic pigment for colored concrete and mortar

The state of Para is one of the greatest producers of mineral substances in Brazil. Kaolin for paper coating industry and bauxite for alumina and aluminium production are amongst the most important commodities. The latter is responsible for the generation of red mud, a well-known residue from Bayer process. The kaolin processing plants are also responsible for the generation of large amounts of wastes, in this case, very fine-grained kaolinite (white mud). The research aimed to find a final destination for such residues by developing new building materials. The proposed material is a pozzolanic pigment produced through calcination and grinding of mixtures of red mud and kaolin waste. The pozzolanic pigments provided increased mechanical strength and color stability of the colored mortars relative to the inert pigment. The pozzolanic characteristics of the pigments reduced the leaching of the mortars. The new material has proven to be promising in its application as an innovative construction material, with the possibility of using these residues in a market that is little explored in Brazilian civil construction: colored mortars and concrete.

The influence of white mud on the water absorption, surface wettability, mechanical, and dynamic thermomechanical properties of core–shell structured wood-plastic composites

The influence of white mud on the water absorption, surface wettability, mechanical, and dynamic thermomechanical properties of core–shell structured wood-plastic composites

Effect of White Mud Addition on Desulfurization Rate of Molten Steel

Fluorspar (CaF2) is commonly used to control the fluidity of slag in ladle-refining of steel. However, because it is desirable to reduce CaF2 consumption because of its environmental impacts, the industrial waste material such as white mud (WM) was investigated as a potential substitute for fluorspar. Steel sample (Fe-0.3C-0.9Mn-0.3Si-0.03Al-0.05S, mass pct) was melted in a high-frequency induction furnace, followed by additions of ladle slag (CaO-Al2O3-SiO2-5MgO-xCaF2, CaO/Al2O3=3, x = 0 to 10 mass pct) and fluxing agent (WM) at 1823 K (1550 °C). The desulfurization experiments were carried out by reducing CaF2 content in the ladle slag and increasing the addition of WM. Ladle slag with added WM showed an overall mass transfer coefficient of sulfur (kO) equivalent to or higher than that of conventional 10 mass pct CaF2-containing ladle slag. In a slag melting experiment based on DIN 51730 standard, the melting rate of mixed slag increased with the amount of WM added, which is considered to have a positive effect on the initial desulfurization rate. In addition, adding WM provided sulfide capacity of the slag equivalent to that of CaF2-containing slag. Consequently, the use of WM yielded slag having k_{{text{O}}} equivalent to or higher than that of conventional ladle slag with 10 pct CaF2, and thus, WM shows promise as a partial replacement for fluorspar.

Effect of Industrial Waste Fluxes (Red Mud and White Mud) on Dephosphorization and Refractory Corrosion: Applications to Electric Arc Furnace Process Using Direct Reduced Iron

Effect of Industrial Waste Fluxes (Red Mud and White Mud) on Dephosphorization and Refractory Corrosion: Applications to Electric Arc Furnace Process Using Direct Reduced Iron

Evaluation of microorganisms associated with vended frozen fish in Ado Ekiti locality

Fishes are world widely consumed by all categories of works of life because of their richness in protein, readily available and affordable by all. The basic nutrient of protein in fish that is so important in man’s diet also attracted microorganisms for their growth and multiplication. Meanwhile, the association of microorganisms in fishes depend on the environment of culture and their proliferation due to inadequate storage facilities. The aim of this study was focused on the isolation and identification of microorganisms from four frozen fish species sold in the Ado Ekiti metropolis. Frozen fish samples of Scomber scombrus (Atlantic Mackerel), Clupea harengus (Atlantic herring), Urophycis tenuis (White hake or mud hake) and Trachurus trachurus (Atlantic horse mackerel) from two markets in Ado Ekiti were microbiologically analyzed for possible microbial contamination. On the fish samples, the total heterotrophic count (THC) was 3.5×104 – 5.6×104 CFU/g, total coliform count (TCC) was 2.4×104 – 5.1×104 CFU/g, total Salmonella/Shigella count (TSSC) was 1.3×104 – 3.5×104 CFU/g, total Vibrio count (TVC) was 1.1×104 – 2.3×104 CFU/g and total fungal count (TFC) was 1.3×103 – 2.3×103 Spore/g were analyzed by cultural methods. There were variations in microbial loads among the fish species in the surveyed markets. The microorganisms identified with their percentage occurrence were Bacillus cereus (11.54%), Streptococcus faecium (13.46%), Alcaligenes faecalis (5.77%), Salmonella enterica serovar Typhi (5.77%), Micrococcus luteus (9.62%), Vibrio cholerae (7.69%), Aerococcus viridans (3.85%), Pseudomonas aeruginosa (7.69%), Xanthomonas fragariae (7.69%), Staphylococcus aureus (11.54%), Clostridium butyricum (7.68%), Escherichia coli (7.69%), Aspergillus fumigatus (11.11%), Aspergillus flavus (24.44%), Aspergillus clavatus (8.89%), Aspergillus fishcheri (6.69%), Aspergillus terreus (8.89%), Mucor mucedo (17.78%), Penicillium digitatum (13.33%) and Aspergillus parasiticus (8.89%). The results emphasized the microbial contamination of the fishes. The results obtained could serve as an awareness to consumers that microbial infection is possible from frozen fishes and as data for future reference in epidemiology or outbreak of disease from eating frozen fish.

Chemo-mechanical properties of alkali-activated slag/fly ash paste incorporating white mud

White mud (WM) is a waste solid from paper industry. It mainly contains calcium carbonate and residual alkali metal ions (e.g., K+, Na+ and Mg2+). The aim of the study was to test the feasibility of incorporation white mud into a blended slag/fly ash alkali activated binder system. Blends of slag and fly ash was used as the precursor and WM was used as the filling material. Pastes with 0%, 10%, 20%, 30%, 40% and 50% WM were prepared for the investigation. It was found that the compressive strength decreases with the WM content increasing. Nevertheless, the paste containing 50% percent of WM is still comparable with Portland cement 42.5. Besides, XRD, TGA, FTIR, SEM/EDX tests were performed. The results indicated that the main reaction product of AASFW is a C-(N)-A-S-H type gel, and the formation of hydrotalcite is promoted as the increment of white mud replacement. In the end, nanoindentation reveals that the addition of WM leads to the histogram of both elastic modulus and hardness shifts towards lowers values. This supports the observation at meso-scale. It is expected that the current study provides an insight into the alkali activated slag/fly ash/white mud binder material and offers a sustainable solution for effective utilization of WM.

Effect of different shell materials on the mechanical and thermal properties of core-shell structured bamboo-plastic composites

The purpose of the study was to inspect the mechanical and thermal properties of four kinds of core-shell structured bamboo-plastic composites (BPCs). The materials that were used for the fabrication of the BPCs were high density polyethylene (HDPE), bamboo pulp fibers (BPF)/HDPE, nano-CaCO3/HDPE, and white mud (WM)/HDPE. As verified by flexural properties and impact properties, the dispersion of the BPF, nano-CaCO3, and WM in the HDPE matrix was inhomogeneous. The fracture surface of the scanning electron microscope (SEM) images showed that some aggregates existed in the HDPE. Additionally, X-ray diffraction (XRD) was used to corroborate the results. The thermogravimetric analysis (TGA) showed that the samples with the WM/HDPE shell has little effect on the thermal stability. However, the apparent activation energy (Ea) values of the nano-CaCO3/HDPE shell were higher than those of the other samples, which indicated better thermal stability. The thermal stability had no remarkable changes with the addition of the WM and BPF. The differential scanning calorimeter (DSC) curves revealed that the relative crystallinity of the BPCs increased with the addition fillers, which suggested that the fillers can act as nucleating agents.