The difficulty with coal water slurry is that high solids and low viscosity have to be met at the same time. The finer the coal and the higher the concentration, the more readily it flocculates and settles, and pumping and atomisation run into trouble behind it.
On the dispersant line, Chemi Tech's workhorses are the KMT series, supplying slurry-making solutions for gasification feedstock, coal water slurry and high-solids mineral slurries. They are matched to coal type, particle size distribution and the water used for slurry preparation.
Business Advantages
First, slurry concentration runs high and the same viscosity carries more solids. Dispersion efficiency is high, so concentration can go up while viscosity stays controllable and gasification efficiency improves.
Second, stability is good: no settling or stratification on standing. Adsorption on the particle surface is stable, so long storage and pipeline transport do not produce a hard pan.
Third, compatibility is good and it does not fight stabilisers. It runs smoothly with common stabilisers and pH adjusters, which leaves more room to adjust the slurry recipe.
Fourth, it tolerates water quality swings and works with reclaimed water. It is more forgiving of changes in preparation water hardness and ion content, so the recipe does not have to be rewritten repeatedly.
Boundary on these figures: the conclusions come from common bituminous coal and gasification slurry conditions. Change the coal type or the particle size distribution and they differ. Run a slurry-making trial before putting it into service.
Industry Pain Points and Solutions
Stability in coal water slurry comes down to coal type swings, water quality swings and a narrow dosage window arriving at the same time. Lose grip on any one of them and the slurry settles again.
Pain point one: change the coal and it settles. Slurry concentration and viscosity shift widely and a hard pan appears on the tank bottom quickly. The answer is a widely adaptable dispersant type, with coal analysis as a prerequisite.
Pain point two: reclaimed preparation water makes performance worse. Ions accumulate in the water and dispersion efficiency falls. The answer is greater tolerance of water quality swings.
Pain point three: too little is not enough and too much re-flocculates. The dosage window is narrow and hard to hit on site. The answer is to make the window real: fix the range first, then fine-tune.
The three-step adaptation method works like this here: analyse the coal and the water first, then run a slurry-making trial, and finally fix the grade and the addition method.
Typical Conditions and Verification
Gasification slurry concentration usually runs around sixty percent, slurry preparation and transport sit near ambient temperature and the slurry rests in the tank before pumping. Settling problems usually show up after storage and tank transfer.
Failure signals tend to circle a few things: a hard pan on the tank bottom that will not stir up; apparent viscosity rising; pump pressure fluctuating more; atomisation nozzles blocking. Match two and a fresh slurry-making trial is due.
Slurry-making records at the same coal type and the same water are available from the technical team, with measured concentration and standing stability both documented.
FAQ
Q1: Why can't coal water slurry use a construction water reducer instead of a dispersant?
Water reducers are mostly designed around cement systems. Adsorption and dispersion efficiency on coal particle surfaces is low, bottom settling is more pronounced, and over the long run it does not pay.
Q2: Can too much dispersant actually make the slurry less stable?
It can. Past a point the particle surface adsorption saturates and flocculation and stratification follow. Set the addition range from the viscosity curve in the slurry-making trial rather than from a single point result.
Q3: How should a coal chemical plant move from an imported dispersant to a domestic one?
Record the original product's addition rate and slurry concentration as a baseline, reproduce the slurry performance on the same coal sample, then run a parallel tracking period and scale up once standing stability matches.