Yield Stress Of Slurries Research Articles

Application of lubrication theory to determine yield stress in slump tests

The slump test can determine the yield stress of slurries by measuring the slump height. The convex shape in the slumped slurry profile cannot be characterised by the Tresca criterion. Lubrication theory has been widely applied to analyse the slow flow of yield stress fluids. Thus, the present study incorporates lubrication theory and the Tresca criterion to establish a generalized model for reconstructing the slurry profile based on the yield stress. The convex profile in the lower zone can be well represented by the novel method. The predicted yield stresses by the slump tests are larger than those determined using the vane method. Slump height and spread are equally accurate for predicting yield stress via the proposed method. Overall, the combination of lubrication theory and Tresca criterion yields a good prediction of yield stress based on slump height.

Study on the hydrate growth characteristics and rheology of silica-containing sand water-in-oil emulsion system

Understanding the transportability of silica-sand-containing hydrate slurries is crucial for production safety of non-consolidated natural gas hydrate reservoirs, especially when solid-state fluidization technology is utilized. Despite some research on silica sand and marine sediments’ influence on hydrate formation kinetics, rheological studies are scarce for systems with silica sands. The formation process of cyclopentane hydrates under the coexistence of hydrophilic silica particles and surfactants were observed. The effects of the concentration and particle size of silica sands as well as the water cut and surfactant concentration of emulsion on the rheological properties of hydrate slurries were investigated using a rheometer. The results indicated: (1) Hydrophilic sand aggregates were entrapped in water droplets, indirectly affecting the oil–water contact area due to the increase in water droplet volume, which was conducive to the combination of alkanes and water molecules to form a hydrate shell; silica particles provided nucleation sites at the oil–water interface to promote the adsorption and aggregation of cyclopentane molecules. (2) The synergistic effect of silica sand and surfactants significantly shortened the induction time of hydrates and increased the viscosity of the slurry. As the concentration of silica sand (1 wt%, 5 wt%, 10 wt%) increased, the induction time of hydrate formation decreased by 44.8 min. Within the concentration range below 5 wt%, the viscosity of the slurry increased as the concentration increased, with an amplitude of 13830.7 mPa·s. The induction time of hydrate formation decreased with increasing silica sand particle size (2 μm, 6.5 μm, 12 μm), but the size of silica sand particles had no significant effect on the viscosity of the slurry. (3) Hydrate slurries in all systems exhibited shear-thinning behavior. There was no obvious relationship between the yield stress of slurry under different silica sand concentrations. However, the yield stress of the slurry was inversely proportional to the size of silica sand particles. The yield stress decreased by 141.13 Pa when the size of silica sand particles increased from 2 μm to 12 μm. Overall, this study highlighted the influence of silica sand presence on flow safety assurance in solid-state fluidization technology.

Multisolid waste collaborative production of aeolian sand-red mud-fly ash cemented paste backfill

This study proposed the novel idea of anaolian sand-red mud-fly ash cemented paste backfill (ARFCPB) to realize low-carbon backfill mining. This idea realizes large-scale disposal and resource utilization of red mud (RM) and fly ash (FA) solid wastes. The influence of the FA/RM mass ratio and mass concentration on the mechanism of action of ARFCPB was explored through comprehensive rheological performance, mechanical property, microscopic, and leaching toxicity tests. The results showed that the fresh ARFCPB slurry could be described by the Herschel–Bulkley model (R2 ≥ 0.964). As the FA/RM mass ratio increased, the ARFCPB slurry yield stress decreased, the thixotropy decreased, and the slump increased. This is because RM has a large specific surface area and an unsmooth surface, resulting in greater water absorption by RM than by FA. In addition, the uniaxial compressive strength (UCS) of ARFCPB can meet the needs of backfill mining with higher strength requirements. UCS first increases and then decreases with increasing FA/RM mass ratio, which is optimal when the mass ratio of FA to RM is 4. When the FA/RM mass ratio was 4, the UCSs of specimens A4 and B4 with mass concentrations of 78% and 80%, respectively, were 5.6 MPa and 6.4 MPa after 28 days of curing. The leaching results of heavy metal ions in group B4 meet the Class III groundwater standards and can be used for centralized drinking water sources and industrial and agricultural water. Considering the fluidity characteristics, mechanical properties, and leaching results, B4 was identified as the optimal formulation. Finally, the microstructure of the ARFCPB was studied using ultrasonic pulse velocity (UPV) and SEM. The results can contribute to clean production in the aluminum production industry, coal-fired power plants, and coal mines.

Rheology Properties of Cyclopentane Hydrate Slurry in the Presence of Wax Crystals

ABSTRACT There are several flow assurance problems for the energy development in deep-water, the coexistence of wax and hydrate resulting to multi-solid phase deposition is among the most difficult to overcome. The results of an experimental study on the effect of wax content, water cut, subcooling and static time on the CP hydrate-forming mixtures are reported. The droplet distribution at different wax contents is determined by using microscopic observation method. Using dynamic stress measurements method, a correlation between rheological properties and water cut is obtained. Hydrate nucleation, growth, dissociation, and slurry rheological properties, including critical time, growth time, final viscosity, and yield properties are determined. Results indicated that wax inhibit hydrate nucleation and growth, but the viscosity of hydrate slurry in waxy system is still higher than wax-free system due to the wax-hydrate aggregates contribute more to the viscosity of the system. The structure of hydrate slurry containing wax system is more stable and more difficult to be damaged by shear. Wax increases the hydrate slurry yield stress, and this effect is more significant at higher water cut and longer static times. The yield stress of the hydrate slurry was linearly related to the water cut. 35% was the critical water cut. Below the critical water cut, the slurry had better flow ability and less yield stress. Above the critical water cut, the yield stress increased significantly with water cut. The yield stress increased with increasing static time and decreases with increasing temperature. Nevertheless, the coupling effect of temperature with water cut and wax content was complex. Below 3 wt% wax content, temperature only has a significant effect on the yield stress of slurries with 40% and 50% water cut. Above 3 wt% wax content, temperature has a significant effect on the yield stress of all slurries with a 20–50% water cut. No ice formation in the CP hydrate-forming mixtures at −4°C, and the dissociation temperature of the hydrate decreases as the concentration of CP in the oil phase decreases.

Study on Dispersion, Adsorption, and Hydration Effects of Polycarboxylate Superplasticizers with Different Side Chain Structures in Reference Cement and Belite Cement.

To investigate the effects of Reference cement (RC) and Belite cement (LC) systems, different molecular structures of polycarboxylate ether (PCE) were prepared through the free radical polymerization reaction and designated as PC-1 and PC-2. The PCE was characterized and tested using a particle charge detector, gel permeation chromatography, a rotational rheometer, a total organic carbon analyzer, and scanning electron microscopy. The results showed that compared to PC-2, PC-1 exhibited higher charge density and better molecular structure extension, with smaller side-chain molecular weight and molecular volume. PC-1 demonstrated enhanced adsorption capacity in cement, improved initial dispersibility of cement slurry, and a reduction in slurry yield stress of more than 27.8%. LC, with its higher C2S content and smaller specific surface area compared to RC, could decrease the formation of flocculated structures, resulting in a reduction in slurry yield stress of over 57.5% and displaying favorable fluidity in cement slurry. PC-1 had a greater retarding effect on the hydration induction period of cement compared to PC-2. RC, which had a higher C3S content, could adsorb more PCE, leading to a greater retarding effect on the hydration induction period compared to LC. LC and PC-2, on the other hand, exhibited inhibition during the hydration acceleration period. The addition of PCE with different structures did not significantly affect the morphology of hydration products in the later stage, which was consistent with the trend of KD variation. This indicates that the analysis of hydration kinetics can better reflect the final hydration morphology.

Assessment on the reverse circulation performance of slurry shield pipeline system assisted with CFD-DEM modeling under sandy cobble stratum

Reverse circulation of slurry shield pipeline system is one of the most effective method to solve slurry chamber clogging during shield tunneling in cobble stratum. In this paper, the assessment on reverse circulation performance of slurry shield pipeline system was performed using the computational fluid dynamics-discrete element (CFD-DEM) coupling approach. In the CFD-DEM coupling model, the shape and size of large irregular cobble particles were considered via 3D scanning technology. In addition, a parametric analysis was conducted, and the effects of the cutterhead rotational speed, slurry inlet velocity and rheological properties of slurry on the reverse circulation performance were investigated respectively. The results indicate that, the magnitude of impact on reverse circulation is in the order of slurry inlet velocity v > slurry plastic viscosity k > cutterhead rotational speed r > slurry yield stress τ0 > slurry power law index n among the working parameters of slurry shield and the Herschel-Bulkley (HB) rheological parameters of the slurry, and the time of reverse circulation is also of importance to the performance of the reverse circulation. Accordingly, a reasonable reverse circulation scheme was suggested, and applied to practical engineering. The findings in this study could provide some references for slurry shield pipeline system reverse circulation of similar projects in the future.

Slurry rheological behaviors and effects on the pore evolution of fly ash/metakaolin-based geopolymer foams in chemical foaming system with high foam content

Interstitial slurry rheology significantly influences the pore structure of chemically foamed geopolymer foams (GPFs). However, the relationship between these two factors has not been elucidated completely. To achieve a range of slurry rheological properties, different metakaolin/fly ash ratios were used, and a high-foam-content system was realized using a H2O2 solution. The slurry rheological properties, foaming properties, and pore structures of the GPFs were tested to establish the influence mechanism of rheology on bubble behavior and pore structures from the perspective of foaming systems. Moreover, equations describing the relationship between the internal and external bubble pressure, extrusion pressure, and slurry yield stress are discussed from the perspective of a single bubble. Four sequential phases of bubble deformation were identified during the foaming process, namely, bubble nucleation, extrusion, expansion, and solidification. The intrinsic relationship between the interstitial slurry rheology and final pore structure of the GPF established herein will provide essential guidance for designing and synthesizing porous cementitious materials.

Analysis of Energy-Saving Transport Conditions of Light-Particle Slurry

Ice slurry, as a new environmentally friendly cold storage medium, is widely used in the field of cold storage and air conditioning because of its excellent flow and heat transfer characteristics. Based on experimental data of slurry flow, the rheological properties of light-particle slurries composed of polyethylene particles and water were analyzed using the response surface method. Using the yield stress and viscosity as the responses and considering three key influencing factors (solid-phase content, particle size, and pipe diameter) simultaneously, the order and law influencing the rheological factors were found. This was a new attempt to find energy-saving conditions for light slurry particle transport using the response surface method. The results showed that the response surface method can select the minimum working condition of mixed slurry viscosity and yield stress to ensure the safe and energy-saving transport of slurry. Moreover, it was also found that the main factor influencing slurry yield stress is the pipe diameter, and the yield stress increases with increasing pipe diameter. The main factor influencing slurry viscosity is particle size, and the viscosity increases with increasing particle size.

Experimental study on rheological behaviors of Na-bentonite slurries under seawater intrusion

During the construction of submarine tunnels, the phenomenon that the seawater contaminates slurries is inevitably encountered. This will lead to obvious deterioration in rheological properties of the slurry, and even cause tunnel face instability. This study aimed to identify the constitutive relationship and rheological characteristics of slurries under seawater intrusion using laboratory experiments. Carboxymethyl cellulose (CMC) was selected as the effective additive to slurries in this paper. Mixtures of Na-bentonite slurries, CMC, and seawater in different ratios were prepared. The viscosity, flow curve, rheological model and physical stability of slurry samples were studied. Furthermore, the viscosity enhancement mechanisms of additives in freshwater and seawater slurries were also investigated. The results show that the increase of CMC and Na-bentonite contents can both greatly enhance the viscosity and make the shear-thinning behavior of slurries more obvious. The exponential equation and linear equation can be used to describe the growing relationships between the yield stress of slurries and the contents of Na-bentonite and CMC, respectively. In addition, the accuracy of the Bingham model predictions in the flow pattern of freshwater slurries was reduced when the viscosity was relatively high. At this time, the constitutive relationship can be better described by the Herschel-Bulkley model. Moreover, seawater intrusion significantly deteriorated the rheology and physical stability and changed the flow pattern of slurries. CMC played a more obvious role in altering the rheological model and increasing viscosities of slurries mixed with less seawater, which can effectively alleviate the deterioration in rheological behavior and maintain physical stability. Microscopically, CMC can make agglomerations more compact and continuous due to the formation of hydrogen bonds with bentonite particles, thus guaranteeing the swelling of bentonite particles and maintaining the excellent rheological properties of slurries contaminated by seawater. This research can provide significant guidance for the establishment of slurry infiltration theories and numerical models under seawater intrusion.

Effect of Flocculants Residue on Rheological Properties of Ultra-Fine Argillaceous Backfilling Slurry

Tailings concentration is indispensable for backfilling. Additionally, the residual flocculants in the concentration process affect the rheological properties of ultra-fine argillaceous backfilling slurry (e.g., viscosity and yield stress), resulting in a great effect on the fluidity and resistance of pipeline transportation. In this study, to explore the effect of flocculants residue on the rheological properties of the slurry, a series of rheological tests (constant shear rate test and variable shear rate test) were performed by changing the type, dosage, stirring time, temperature of flocculants addition and the amount of binder added. The results showed that the addition of flocculants increased the viscosity and yield stress of slurry. At a certain amount of flocculants additive, the flocculant network structure reached the best development state, which had a positive effect on increasing slurry viscosity and yield stress. As the stirring time increased, the scale of damage to the flocculant network structure became larger, which had a negative effect on increasing slurry viscosity and yield stress. Low temperature weakened the adsorption and bridging effect of polymeric chains, resulting in a poorly developed flocculant network structure, which had a negative effect on increasing slurry viscosity and yield stress. Caused by hydration products, the viscosity and yield stress of slurry with binder further increased. This study is significant for an in-depth study of the rheological and pipeline transport characteristics of ultra-fine argillaceous backfilling slurry, optimising the selection of flocculants for ultrafine particles, guiding backfill parameters and improving the reliability of pipeline transport.

Determination of Static and Dynamic Yield Stress of Chengdu Clay Slurry

The yield stress of mud is one key to analyze the initiation and deposition of debris flow. Taking Chengdu clay as the experimental material, slurries with different solid volume concentrations were prepared. Using the blade rotor system of mcr301 rheometer and the continuous shear experimental method, the dynamic change process of shear stress of slurries with different solid volume concentrations was obtained with the shear rate increasing and decreasing continuously. According to the experimental results, the static and dynamic yield stress of Chengdu clay slurry is determined, and the influence of solid volume concentration on the yield stress is analyzed. The following conclusions are obtained: Chengdu clay slurry is a non-Newtonian fluid with yield stress. In the process of accelerated shear, for Chengdu clay slurry with solid volume concentration exceeding 35%, the shear rate is in the range of 0.01–1 s−1, and the shear stress increases rapidly to the maximum. When the shear rate exceeds 1 s−1, the shear stress decreases rapidly and finally tends to be stable. The shear rate appears stress overshoot near 1s−1. However, in the process of increasing shear rate, for Chengdu clay slurry with solid volume concentration of no more than 35%, the shear stress increases rapidly in the range of shear rate of 0.01–0.1 s−1, and the shear rate exceeds 0.1 s−1. The shear rate has little effect on the shear stress, and the stress overshoot disappears. In the process of deceleration shear, for all solid volume concentrations in the semi logarithmic coordinate system, the mud shear stress decreases steadily with the decrease of shear rate. The static and dynamic yield stress of slurry increases exponentially with particle concentration.

Rheological properties of cemented paste backfill and the construction of a prediction model

The Cemented Paste Backfill (CPB) yield stress is a key rheological parameter for paste filling technology, which has significant practical value for pipeline optimization and equipment selection of pipeline conveying systems. However, the slurry yield stress is affected by many factors. In order to accurately analyze and predict the CPB yield stress, this study uses the sparrow search algorithm to optimize the relevance vector machine (SSA-RVM) and proposes the prediction model of SSA-RVM CPB yield stress regression. Based on 136 sets of rheological tests for copper mine, different waste rock/tailing sand ratios, mass concentrations, and water-cement ratios select to predict the yield stress at different training set ratios (78%, 85%, 92%). Compared with the traditional relevance vector machine (RVM) regression model, the SSA-RVM regression prediction model has higher prediction accuracy. In addition, the coefficient of determination R2 of the predicted and true values obtained from the SSA-RVM model increased by 0.0407, 0.0438, and 0.0500 for the training set ratios of 78%, 85%, and 92%, respectively. The results suggested that SSA-RVM can efficiently predict the CPB yield stress, which can be a reference for the design of paste-filled pipe conveying systems.

Rheological Properties of Ultra-Fine Tailings Cemented Paste Backfill under Ultrasonic Wave Action

Ultra-fine tailings cemented paste backfill (UCPB) exhibits special rheological characteristics with the effect of an ultrasonic sound field. In this study, in order to explore the thickening effect of slurry under ultrasonic wave action, we examined the rheological properties with ultrasonic wave tests of UCPB and the rheological properties after ultrasonic wave tests of UCPB. We found that the rheological curve of the slurry changed; the Herschel–Bulkley (HB) model in the initial state transformed into the Bingham model under the action of ultrasound. Ultrasonic waves have a positive effect on reducing slurry viscosity and yield stress. The rheological test of the slurry with ultrasonic wave action had a positive effect on significantly reducing the apparent viscosity and initial yield stress of slurry with a 62% mass concentration. The rheological test of slurry with ultrasonic wave action and the rheological test after ultrasonic wave action both have positive effects on reducing the viscosity and yield stress of the slurry with a 64% to 68% mass concentration; the overall effect of reducing the viscosity and yield stress of UCPB is greater after ultrasonic wave action of UCPB.

Effects of water content, water type and temperature on the rheological behaviour of slag-cement and fly ash-cement paste backfill

The pumping ability and placement performance of fresh cemented paste backfill (CPB) in underground mined cavities depend on its rheological properties. Hence, it is crucial to understand the rheology of fresh CPB slurry, which is related to CPB mixture design and the temperature underground. This paper presented an experimental study investigating the effects of binder type, content, water chemical properties and content, and temperature, on the rheological properties of CPB material prepared using the tailings of a copper mine in South Australia. Portland cement (PC), a newly released commercially manufactured cement called Minecem (MC) and fly ash (FA) were used as the binders added to the mine tailing materials. Various amounts of two different water types were added to the mixtures in the preparation of backfill material slurry. Six different temperatures ranging from 5 to 60 °C were to investigate the effect of temperature on CPB rheology. Overall, the increasing water content and decreasing temperature lead to lower yield stress. Based on the results obtained from the rheological properties of CPB slurry, it was found that at room temperature (25 °C), with regards to the unconfined compressive strength (UCS) performance, the replacement of 4% PC mixed CPB (28 days UCS 425 kPa) to 3% MC mixed CPB (28 days UCS 519 kPa), reduced the slurry yield stress from 210.7 to 178.5 Pa. The results also showed that the chemical composition of water affects the yield stress of CPB slurry and that MC mitigates the negative effect of mine-processed water (MW) and thus lead to improve the rheological properties of the slurry. However, the results suggested that the rheological properties of a mixture using MC is very sensitive to the water volume and temperature change. Therefore, using MC in backfill requires better quality control in slump mixing.

A significant improvement of fine scheelite flotation through rheological control of flotation pulp by using garnet

The paper proposes a novel method which utilizes the garnet to realize the rheological control of the flotation pulp in fine scheelite flotation. The garnet was added in the conditioning operation of the cleaning flotation stage. Sodium oleate and water glass were used as flotation collector and depressant, respectively. Flotation tests on the cleaning flotation with different addition of garnet were conducted, coupled with rheological measurements, flotation rate calculation and optical observations on the corresponding flotation pulp and froth. It is found that there exists strong correlation among the flotation rate, pulp rheology, froth and floc morphology in the cleaning flotation. As the garnet content in the cleaning flotation pulp increases, the viscosity of the flotation pulp decreases and the flotation rate increases; the floc morphology changes from big-branch type to globule-like and the flotation froth becomes cleaner. It is also found that the changes in the fluid properties of the flotation slurry caused by the garnet addition are closely related to the flotation selectivity. As the slurry yield stress decreases and the flotation slurry deviates nearer to the Bingham fluid, the flotation rate increases and the flotation selectivity improves. The results could potentially be used to improve the flotation performance of fine scheelite ore through rheological control of flotation pulp by garnet addition in cleaning flotation operations.

Experimental study on fluid properties of slurry and its influence on slurry infiltration in sand stratum

Abstract In construction of slurry engineering, especially in sand stratum of high permeability, small size fine particles in slurry are likely to flow through the stratum and washed away. In this study, nine groups of slurry fluid property tests were performed using a NXS-11A rotary viscometer in order to investigate infiltration of slurry in sand stratum. Additionally, a series of penetration tests were also conducted by a self-designed infiltration device. Experimental results show the test slurry meet characteristics of Bingham fluid at a medium to high shear rate, while it conforms to the Herschel-Bulkley model at a low shear rate. Darcy's law is no longer applicable to infiltration of slurry in sand stratum, because of the initial hydraulic gradient. The infiltration rate (vs) is not strictly linearly related to the hydraulic gradient at small hydraulic gradient (i). It is also indicated that the yield stress of slurry is the fundamental cause of initial hydraulic gradient during the infiltration process of slurry in sand stratum. The yield stress has a positive correlation with the initial hydraulic gradient. Ideally, initial hydraulic gradient is proportional to the dynamic shear force of slurry.

Preparation of polycarboxylate-based superplasticizer and its effects on zeta potential and rheological property of cement paste

A series of polycarboxylate-based superplasticizers (PCs) with different structures were synthesized and the effects of chemical structure on zeta potential and rheological property of cement paste were studied. Residual monomers in each sample of PCs were quantitatively determined. The property of the polymers in cement was tested by micro-electrophoresis apparatus and R/S rheometer. Results showed that the zeta potential and its rheological properties are related with the side-chain length and density of PCs. The PCs having shorter side chain and lower side chain density exhibit higher anionic charge density, thus resulting in higher zeta potential. The effect of side chain density on zeta potential is more notable compared with that of side-chain length, and thus affecting the initial shear yield stress and apparent viscosity of the cement paste. In addition, although increasing the side chain length will result in reduction of the anionic charge density, the steric hindrance effect is obvious, which can effectively improve the dispersion of the cement particles, and reduce the viscosity and shear yield stress of slurry.

Ultra-fine grinding and mechanical activation of mine waste rock using a high-speed stirred mill for mineral carbonation

CO2 sequestration by mineral carbonation can permanently store CO2 and mitigate climate change. However, the cost and reaction rate of mineral carbonation must be balanced to be viable for industrial applications. In this study, it was attempted to reduce the carbonation costs by using mine waste rock as a feed stock and to enhance the reaction rate using wet mechanical activation as a pre-treatment method. Slurry rheological properties, particle size distribution, specific surface area, crystallinity, and CO2 sequestration reaction efficiency of the initial and mechanically activated mine waste rock and olivine were characterized. The results show that serpentine acts as a catalyst, increasing the slurry yield stress, assisting new surface formation, and hindering the size reduction and structure amorphization. Mechanically activated mine waste rock exhibits a higher carbonation conversion than olivine with equal specific milling energy input. The use of a high-speed stirred mill may render the mineral carbonation suitable for mining industrial practice.

Study on Parameters of Slurry Pipeline Transportation Technology in Grade

In generally, there are multiple factories. According to mining areas, it supplies different quality iron ore concentrate. And according to the unique requirements of owners, different grades concentrate cannot be confused. Therefore, the grade of slurry pipeline transportation is needed to be used. When in the study of grade transmission, we must focus on Hydraulic characteristics of solid-liquid two-phase for different quality of iron ore concentrate. Slurry concentration and Critical velocity of flow is especially important. Research shows that the deposition rate of laminar or turbulent transition velocity is higher than the occasion when the slurry has concentration, so the minimum operating speed is controlled by sedimentation; the concentration lower limit is 62%. If the concentration is over 68%, the yield stress of slurry will increase, and the pipeline pressure will drop, which is very sensitive to slight changes in concentration. Therefore, the solid weight concentration range is 62% to 68%,as the selection range of design.

The impact of zinc recycling on the slurry rheology of WC–6 wt.% Co cemented carbides

The slurry rheology of zinc recycled and new WC–6wt.% Co materials has been studied. The impact of polymer molecular weight, particle size distribution, zeta potential and solids loading on slurry rheology has been investigated and correlated with spray dried powder properties. Powders were characterized in terms of granule size distribution, apparent density, flow rate and granule microstructure. Zinc recycled and new powders, produced in both laboratory and production sized mills, were rheologically tested at various particle sizes ranging from 1.3μm to 4.1μm and at 3 different alcohol fractions. Polymer breakdown did not occur during milling, and did not influence slurry rheology. Recycled powders exhibited more consistent zeta potentials compared to new powders however all of the slurries, recycled and new alike, displayed agglomerating tendencies. Grain size distribution was shown to be the dominant factor in the shear response and development of a slurry yield stress, which resulted in solid spray dried granules from slurries possessing finer grain size and a higher yield stress, compared to hollow granules resulting from slurries possessing a coarser grain size and a low yield stress. Finer slurries, regardless of recycling or not, displayed higher settling rates. Zinc recycled slurries settled less quickly than new slurries of similar particle size; however they required longer milling times to achieve the target grain size distribution. Both zinc recycled and new powder slurries can be tailored to produce ideal, solid granules.