The application of most empirical correlations for hydraulic gradient of settling slurry are generally limited to the experimental region in which four different flow patterns can be observed: stationary bed flow, saltation flow, heterogeneous flow, and pseudo-homogeneous flow. Therefore, the reliable design model independent on not only the flow regimes but also pipe diameter is imperative for pipeline engineers.By using the condition factor introduced by Sato et al., which represents the situation of solids movement in a pipe and calculated from the concentration profiles, an equation was derived for hydraulic gradient of settling slurry flow in horizontal circular pipes. With the slurry database, it was also assured that the equation was valid for practical pipeline design under the condition of settling slurry flow. Hence, the effect of pipe diameter and concentration on the Specific Energy Consumption and pipeline design procedure were discussed based on the analytical results.

In designing pipeline systems for commercial slurries, it is essential to accurately determine the hydraulic gradient at transport velocities. It is crucial to note that the slurries are conveyed as a mixture of multi-sized solids and water. Although many researchers have proposed correlations for the prediction of hydraulic gradient, most have been developed for slurries with uniform sized particles of solids.By considering two different transport conditions of a mixed-sized slurry, innovated models were conventional method by Condolios-Chapus. Measurements of hydraulic gradient, solids concentration, and flow velocity in a 1-inch pipeline were made in this study. Predictions with the innovated models could be correlated with the data including

The transport conditions of solids in slurry pipelines cause the flow behavior of solid-liquid mixture to vary strongly and affect the hydraulic gradients in the systems. Since any transport design or correlation for slurry transport should be confirmed by a wide range of data, experiments in various flow regimes have been carried out over the years by different researchers.This study was, therefore, aimed at developing a slurry transport database for accumulation, input, editing, sorting, storing of the data available in literature and displaying the results in graphical form for comparison. A basic processing procedure was adopted for the design of the program. Then a flowchart of the program was developed to process the data. The flowchart consisted of three subflowcharts: input-for the input and addition of data； editing-for modifying and standardizing all the data into the Excel CSV form； and graph displays of the data-for comparison of the researchers' data on log-log graphs. Star graphs were used to give a clear description of the transport conditions for each researcher. The database was applied for the verification of proposed correlations for predicting the hydraulic gradients of slurry flow in pipes.

The paper presents a design procedure for horizontal pipeline systems, such as those used in bulk solids handling/transportation in mining operations.The mean velocity as well as pressure drop are important parameters in the design of the slurry pipeline. Accurate prediction of the parameters is needed for the selection of pipe diameter and the type of pump suitable for the slurry system. The objective of this paper was to provide a pipeline design procedure, especially for mixed-sized slurry flows typically found in the coal mining industry.This study covered the evaluation methods for determining flow regimes, concentrations, and optimum pipe diameter. Critical velocity and transport velocity of flow were also discussed. The innovated models for mixed-sized slurry flows by Seitshiro et al. were applied for the prediction of the hydraulic gradients.In conclusion, the design procedure proposed in this study was verified with field data.