Regarding coal water slurry additives

Most conventional water-coal slurry gasification units use sodium wood sulfonate as an additive; concentrated papermaking waste liquid can also be used!

Generally, sodium lignosulfonate series, naphthalenesulfonic acid series, and so on are added. You can look up the properties by yourself.

Due to differences in coal types and qualities, the types of additives used and their amounts added during the pulping process can vary for different coal types! To date, no additive that can be used universally for all types of coal has been developed; for specific coal types, specialized evaluation tests are required to determine the type of additive and the appropriate dosage that will be most effective for them.

To ensure that water-coal slurry has a low viscosity, good flowability, and does not tend to settle during normal use, a small amount of chemical additives need to be added during the slurry preparation process. Depending on their functions, additives include dispersants, stabilizers, and various other auxiliary chemicals such as defoamers, pH regulators, antifungals, surface modifiers, and accelerators. Among these additives, dispersants and stabilizers are essential. (1) Dispersant A dispersant is a substance that facilitates the uniform dispersion of the dispersed phase (such as coal particles in water-coal slurry) within the dispersion medium (such as water in water-coal slurry). Coal water slurry dispersants are all types of surfactants; they are amphiphilic molecules with a non-polar, lipophilic group (hydrophobic group) composed of hydrocarbons at one end, and a hydrophilic group at the other end. The main function and purpose of a dispersant is to prevent the dispersed particles from aggregating and precipitating, thereby enhancing the stability of the system. The mechanism of action of dispersants can be explained in terms of wetting and dispersion effects, as well as spatial steric or entropy-driven dispersion effects. These various mechanisms do not exclude each other; rather, they complement one another. Water-coal slurry is a mixture of coal and water, and it is an essential prerequisite for its preparation that the surface of the coal particles be fully wetted by water. Coal is a hydrophobic mineral that does not wet easily in water. The non-polar, hydrophobic groups of dispersants can easily bind to the surface of coal, adsorbing on the surface of coal particles and arranging themselves in a specific pattern; the hydrophilic groups at the other end extend into the water, thereby converting the hydrophobic surface of coal into a hydrophilic one. Therefore, the main function of the dispersant is to reduce the surface tension at the solid-liquid interface in the water-coal slurry, thereby altering the surface properties of the coal particles and enhancing their wettability (the hydrophilicity of their surfaces). This allows the surface of the coal particles to be fully wetted by water, resulting in the formation of a stable hydration film on their surface, which facilitates dispersion. Another major function of dispersants is to reduce viscosity, as they adsorb onto the surface of coal particles, forming a thin layer of additive molecules and a hydration film on that surface, which can **reduce the interfacial tension between the coal particles and water**. When the coal particles in water-coal slurry are well dispersed, they remain separated from one another; there is also a strong hydration film on their outer surfaces. No new phase interfaces are formed during shearing, and the friction between the particles is lower than when there are no adsorbed additive molecules or hydration film on their surfaces. Therefore, dispersants can significantly reduce the viscosity of water-coal slurry. (2) Stabilizers: The stability of water-coal slurry refers to the property whereby the slurry maintains a uniform consistency during storage and transportation. Water-coal slurry is not a homogeneous fluid, but rather a solid-liquid mixture; the loss of stability arises from the precipitation of the solid particles within it. The function of the stabilizer is to enable the particles already dispersed in the coal slurry to combine with other surrounding particles and water to form a three-dimensional structure that is weak but still possesses some strength. When the mixture is left at rest, this structure can exert mechanical resistance against the settlement of the particles, effectively preventing such settlement; and even if settlement does occur, it results in a soft, recoverable form of sedimentation. Once subjected to external shear forces that cause the structure to be damaged, its viscosity can drop rapidly. Stabilizers that can perform this function include inorganic salts, polymer organic compounds, and others. The stabilizer should be added separately after the dispersant has been incorporated and the mixture stirred into a slurry. The amount used depends on the properties of the coal and the desired duration of stability, generally ranging from a few ten-thousandths to a few thousandths of the coal volume. (3) Other auxiliary additives: Since dispersants often have foaming properties as well, and the bubbles in water-coal slurry are detrimental to the fluidity of the slurry, an antifoaming agent needs to be added when the dispersant has strong foaming capabilities. Furthermore, the degree of dissociation of the additives in water, as well as their interaction with the coal surface and other substances in the solution, are all related to the acidity or alkalinity of the solution. To achieve better pulping results, it is sometimes necessary to add agents that can adjust the pH value in order to modify the pH of the water-coal slurry; a weakly alkaline solution environment is preferable during pulping. Additionally, to enhance the interaction between the additive and the coal surface, there are also methods to modify the properties of the coal surface, as well as promoters that facilitate the adsorption of the additive molecules onto the coal particle surface. The effect of additives occurs at the coal-water interface of the water-coal slurry. Its effectiveness is closely related to the properties of the coal, particularly its surface properties, the concentration of the water-coal slurry, the particle size, and the properties of water. Therefore, the formula and dosage of additives used in slurry preparation cannot remain constant; a suitable formula and dosage must be determined through experimental research, based on the properties of the coal used for slurry preparation and the quality requirements of the users for the water-coal slurry product. The amount of additives used is usually around 1% of the coal volume, and their cost constitutes the second largest component in the pulp production costs after the cost of coal; therefore, the formula of the additives has a significant impact on the cost of water-coal slurry. Two principles should be followed when selecting additives: the first is to prioritize the best performance-to-cost ratio, rather than solely pursuing the highest efficacy of the additive ； Second, the appropriate additives are determined based on the principle of complementarity between gradation and additives.

During the feasibility study of a project, experiments must be conducted on the slurry-forming properties of the coal types to determine whether they are suitable for water-coal slurry gasification technology; this includes testing different types of additives and their various usage levels.

What was said on the 5th floor is quite comprehensive. However, during the preparation of water-coal slurry, coal types with different degrees of transformation exhibit a certain degree of selectivity regarding additives. When choosing additives for water-coal slurry, it is necessary to take into account factors such as their performance, suitability for different coal types, and cost-effectiveness; conducting experiments is the best way to make such decisions.

The internal water in coal has a significant impact on its slurry-forming properties! To achieve a high concentration of internal water, it should be as low as possible!

Add a dispersant; I sell powdered dispersants