Raw Materials Analyzing

Quality raw materials will be easier success. Fly ash, Tailings, Construction wastes, Shale, River silt, Waste soil, Loess, Life sludge, Gangue.

Primary work for setting up a brick plant :The raw materials chemical composition and physical properties (including the internal combustion heat, etc.) testing, meanwhile measure the moisture of green bricks forming & extrusion.


Chemical Analysis

Chemical composition analysis is usually measured as SiO2, Al2O3, Fe2O3, MgO, CaO, magnesium oxide, sulfur gangue, loss on ignition and etc.


SiO2: Content is too high, lower plasticity, although good for fast-drying, however the finished products with low compressive strength.

Al2O3: If less than 12%, the mechanical strength of the products is reduced, if more than 24%, the firing temperature is increase, increasing the amount of coal.

Fe2O3: Content too high will reduce the products refractoriness, resulting in low of sintering temperature.

CaO:Presenting In a state of CaCo3 in raw materials, classified as hazardous substances, If the particles larger than 2mm, it is likely to cause crisp brick or burst when burning.

MgO: The less the better, otherwise, products easily growing generate magnesium, causing white hoarfrost.

Sulfur Dagan: Being sulphate in raw material, the content should not exceed 1%. When burning, it will make SO2 and corrode production line equipment, harmful for workers’ health.

Loss on ignition:Caused by organics in raw materials. If higher loss on ignition, more hole rate for the products.





Chemical Component SiO2 Suitable 55~70
Available 55~80
Al2O3 Suitable 15~20
Available 10~25
Fe2O3 Suitable 4~10
Available 3~15
CaO Available 0~10
MgO Available 0~3
SO3 Available 0~1
loss on ignition Available 3~15
Calcareous Content <0.5mm Suitable 0~25
2~0.5mm Available 0~2

Physical Performance Analysis: Usually measure particles composed, plasticity, shrinkage, drying sensitivity and sinter ability.


Particles Composed

Particles category

Particle diameter

Reasonable composition

Plastic particles



Filler particles



Skeleton particles



Plasticity: When plasticity index in 7 ~ 15, most suitable for middle plastic mud extrusion.

Shrinkage: Linear shrinkage <6%, if it is too high to crack products, affecting the quality of brick.

Drying sensitivity: The higher raw material plasticity, the finer of the particles, also the higher of drying sensitivity. Sensitivity coefficient determines the drying process design, too high cause green bricks’ surface cracking.


Relationship of forming moisture content and drying sensitivity

Green brick molding moisture



The critical water of green bricks



Drying sensitivity coefficient




In Summary

Chemical analysis of raw materials, physical properties and tests molding moisture decide the feasibility of using raw materials and affect the next process design, equipment selection, kiln structure, product quality and other aspects of the production system.