Rheological Properties of Aqueous Sodium Alginate Slurries for LTO Battery Electrodes

Rheological properties of electrode slurries have been intensively studied for manifold different combinations of active materials and binders. Standardly, solvent-based systems are under use, but a trend towards water-based electrode manufacturing is becoming more and more important. The different solvent is beneficial in terms of sustainability and process safety but is also accompanied by some disadvantages such as extraction of residual humidity and a higher complexity concerning slurry stability. Li4Ti5O12 (LTO) active material provides good long-term stability and can be processed in aqueous solutions. Combining the LTO active material with sodium alginate (SA) as a promising biobased polymer binder reveals good electrochemical properties but suffers from bad slurry stability. In this work, we present a comprehensive rheological study on material interactions in anode slurries consisting of LTO and SA, based on a complex interaction of differentially sized materials. The use of two different surfactants—namely, an anionic and non-ionic one, to enhance slurry stability, compared with surfactant-free slurry.

Reduction of Fractionation of Lightweight Slurry to Geothermal Boreholes

When designing the cement slurry for casing string cementing in geothermal boreholes, the appropriate thermal conductivity is selected. In the zone of geothermal water, where thermal energy is collected, cement slurry is used, from which the cement sheath has high thermal conductivity. On the other hand, the remaining part of the opening is sealed with slurry, from which the cement sheath will reduce thermal energy losses through appropriate thermal insulation. Cement slurry with appropriate thermal insulation includes light insulating materials. However, the use of such additives is very problematic as they are fractionated due to their low density Therefore, measures should be taken to prevent fractionation of the cement slurry for sealing geothermal boreholes. This article presents the results of research on fractionation of cement slurries for sealing geothermal boreholes. 12 slurries were used for the tests. Six of them are based on class A cement, and six based on class G cement. This action shows the differences in fractionation depending on the binder used. However, the main area of research is determining the effectiveness of counteracting fractionation by the means used for this purpose. As a result of the conducted works, a very good improvement of the cement slurry stability is obtained after the introduction of xanthan gum, as well as filtration perlite. These measures prevent fractionation, so that the cement slurry has a homogeneous structure, and the cement sheath provides the required thermal insulation in the geothermal well.

Study on the strength property and ratio parameter selection of waste rock cemented backfill

When tailings are used for cemented backfill preparation, the extremely fine unclassified tailings may lead to slow consolidation and low strength of backfill material. Wasted rock as an additional filling aggregated was suggested to optimize the gradation composition of aggregate by scholars over the world. In this paper, the effect of waste rock addition, cement-tailing ratio and slurry concentration on strength and flow properties of waste rock cemented backfill were studied. The results indicate the strength of waste rock cemented backfill was significantly higher than that of unclassified tailings cemented backfill under same cement consumption, which the average strength improvements were 2.02MPa, 0.98MPa and 0.46MPa under cement-tailing ratio of 1:4, 1:8 and 1:10. With the increase of waste rock addition, the strength change of waste rock cemented backfill was less obvious, but the flow property (yield stress) of filling slurry was improved. Further analysis of the slurry stability illustrates that, with the increase of waste rock addition, the bleeding rate demonstrated a trend similar to that observed for the flow property, however, in an adverse manner. Overall, the optimal slurry concentration of 80% and waste rock addition of 40%～50% were determined. Based on the strength requirement, cement dosage was selected, which the cement-tailing ratio of top 10m and the bottom 10m was 1:8, the cement-tailing ratio of the centre stope was 1:10. The research findings can provide a reference for the ratio parameter determination of extremely fine unclassified tailings backfill of similar mines.

Effect of the Properties of Cordierite Support and Catalyst Slurry on the Catalytic Degradation of Toluene by Monolith Catalyst

Monolithic catalysts are widely used in industrial catalysis. However, in the preparation of monolithic catalyst, the most important catalyst coating has the problems of low upload rate and poor uniformity. In the present work, the effects of acid treatment of carrier on the upload rate and the effects of size of slurry and dispersant on the uniformity of coating were investigated. The weight loss rate and water absorption rate of cordierite, slurry stability, coating upload rate and catalytic performance were also tested. Characterization analysis was carried out by means of BET, SEM, Zeta potential, the laser grain-size analyzer. The results showed that the optimal performance of cordierite carrier could be obtained by heating the cordierite carrier with 20% HCl for 3 h; the water absorption rate could increase for more than 48.0%, and the upload rate could reach 14.5%. Pearson test showed that there was a moderate positive correlation between water absorption rate and upload rate. It was also found that reducing the particle size of the slurry (1.47 microns) and adding 4% dispersant PAA could effectively improve the stability of the suspension and the uniformity of the coating. When 20% HCl was used to pretreat, the toluene catalytic activity of the monolith catalyst prepared by cordierite increased, in which T10 and T90 both increased for about 5 ℃. At the same time, reducing particle size and adding dispersant could also promote the catalytic degradation efficiency to a certain extent.

Liquid Strength Retrogression Control Additive

To mitigate strength retrogression at temperatures, higher than 230°F, well cement designs typically include strength retrogression control additives (SRCAs). Solid siliceous materials (e.g., silica flour, fume, and sized-sands) are commonly used SRCAs that are incorporated into cements using dry-blending techniques. This study highlights liquid silica compositions as alternative SRCAs to dry-blended silica for high-temperature cementing. Liquid additives can be managed easily, delivered accurately, and offer a reduced on-site footprint, thus making them particularly advantageous for operations offshore and in remote locations. This paper presents a study on the use of liquid silica compositions as SRCAs and their effect on cement slurry properties, such as thickening time, mixability, fluid loss, rheology, and free water. The cement slurry used during the current study was prepared and tested according to API RP 10B-2 (2005). The performance of the liquid silica composition was tested at temperatures up to 400°F. Set cement samples were prepared using the liquid silica composition and silica flour, cured for up to 14 days at different temperatures. In addition, permeability testing was also performed on the samples. This paper presents the findings of this research, including strength and permeability test results on cement blends cured at temperatures of 300, 330, 350, and 400°F. The liquid silica composition, which provided silica to the cement formulation equivalent to 35% BWOC dry silica (48% BWOC liquid SRCA), functioned effectively as an SRCA at temperatures up to 330°F. Signs of strength retrogression were observed at 350°F and were more pronounced at 400°F. A greater concentration of the liquid silica composition may be necessary to prevent strength retrogression at temperatures higher than 330°F. The liquid silica composition also demonstrated mild retardation and a dispersing effect on the slurry. However, it helped enable improved slurry stability and suspension, thus providing improved control over free water without adverse effects on fluid loss and sedimentation. The study results demonstrate that a liquid SRCA can help improve the performance of annular cement designs to provide dependable barriers and effective zonal isolation during high-temperature cementing applications. The improved performance enabled by this liquid silica composition verifies its potential use as an alternative SRCA for high-temperature oil well cementing operations.

Effect of Modified Sludge on the Particles Flocculation and Slurry Stability in the Co-slurry of Sludge and Petroleum Coke

Sewage sludge modified by Ca(OH)2 and Fe2(SO4)3 were used as make the slurry with petroleum coke, and changes in the size distribution and a total number of particles in the slurry were determined by Focused Beam Reflectance Measurement (FBRM) to explore the particles flocculation mechanism. In addition, the structural strength of petroleum coke sludge slurry (PCSS) was calculated by two mathematic models to illustrate the how the sludge improves the stability of PCSS. The results indicated that the absolute value of the Zeta potential of PCSS increased with the sludge addition and that PCSS stability improved. However, the absolute value of the Zeta potential decreased and the stability declined after the sludge was modified by Fe2(SO4)3 and Ca(OH)2. Petroleum coke particles were wrapped by sludge flocs, and small particles flocculated during their co-slurry process to form a spatial network structure, effectively prevented the settlement of petroleum coke particles and ultimately improved the stability of slurry. The calculation results obtained by the two mathematic models reveal that the shearing energy consumption per-unit-quality of PCSS using raw sludge is twice or thrice than that of PCWS. However, energy consumption was reduced after the sludge was modified by Fe2(SO4)3.