Re--Reynolds number;
υ _l ———The critical flow rate of slurry transport, m/s;
i _N ———Unit head loss of uniform particle size material, m water column/meter; can be calculated according to formula (11).
b Applicable conditions The Euphen's formula is derived from the particle test data of solid density δ _g = 2.65 ton / m ³ . If the solid density in the slurry is too different from 2.65 tons/ ^m3 , it is not applicable. Moreover, the particle size used in the test ranged from 0.4 to 1.0 mm. Therefore, high concentration fines and tailings are not suitable for use. In addition, the formula is considered according to the particle size unevenness coefficient δ<10. If the δ value is greater than 10, the critical flow rate value obtained is too small, so it should be used with caution.
C Durand formula a Calculation formula

b Applicable conditions The Durand formula is obtained by R. Durand in the hydraulic conveying system test of the round pipe from 1952 to 1954. The test conditions are: the pipe diameter is 19.1 to 584.2 mm, and the flow velocity is 0.61 to 6.1 m/s. The solid particle size is 0.1 to 25 mm. The juice calculation value of this formula is generally considered to be larger than the actual measurement value. However, since the general design is intended to ensure safety, the use value of the formula is not affected. The particle size used in the test of this formula is relatively coarse, and the influence of the particle diameter dp on the critical flow rate Ï…l is not considered. Therefore, the Durand formula is not applicable to the high-concentration slurry mainly composed of fine particles.
In addition to the above three formulas, at home and abroad there are a lot of similar design formulas, such as domestic Jinchuan formula, Beijing General Research Institute for Nonferrous Metallurgy formula based sauce, C.г. Ke Er Nike formula of the Soviet Union do not belong to this class. The common feature of this type of formula is that both the critical flow rate and the unit head loss increase with increasing concentration, reflecting the important feature that the critical flow rate and unit head loss are reduced as the slurry concentration increases to a certain height. In recent years, many experts have tried to derive hydraulic formulas that reflect the characteristics of high-concentration slurries, but there is still insufficient verification of practice. Most of the design parameters for high-concentration slurry transport are obtained through experiments.
The following is a description of several high-concentration slurry transport calculation formulas that have been used in China for reference.
D Ukrainian Institute of Construction Research

G, G ₀ ———The weight of solids and water in the slurry.
The rest of the symbols are the same as before. [next]
E Anshan Black Metallurgical Mine Design and Research Institute formula a Determination of critical pipe diameter

W _i ———the average sedimentation velocity of a certain grain size, cm/s;
a _i ——— percentage of a certain fraction;
W ₉₅ ——— d ₉₅ particle settling velocity, cm / s;
R———hydraulic radius, m;
λ———the drag coefficient; can be calculated by:

D _j ——— Calculate the pipe diameter, m;
υ _j ——— the flow rate corresponding to the calculated pipe diameter, m/s;
υ———the viscosity coefficient of the slurry movement;

Ï… ₀ ———The viscosity coefficient of clean water movement, in the formula (27), the unit is m ² /s;
P _v — the volume concentration of the pulp;
a _i ———% of the weight of a certain grade, if the content is 25%, write a _i =0.25
d _i ———the average particle size of a certain size, cm.

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