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Slag Cement Manufacturing Process

Slag cement is also called blast furnace cement, pbfc cement(Portland blast furnace cement). It is composed of Portland cement clinker, 20%-70% granulated blast furnace slag, and appropriate gypsum. 

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how to make blast furnace slag cement?

Recently, Slag has become an important mixing material of cement, grind ability of slag is very poor. In general, the slag powder is processed by the slag grinding plant in advance, and slag powder will be sent into the cement plant for making slag cement, so it is particularly important to select the appropriate slag grinding plant. The core equipment of slag grinding plant is vertical cement mill.

Slag cement manufacturing process can be normally divided into several steps:

  1. Raw material crushing
  2. raw mill
  3. clinker calcination
  4. clinker grinding
  5. finished cement storage and paking
STEP1: Raw material production

The raw material is sent to the cement crusher, where it is broken or hammered into pieces.

STEP2: Raw mill

In the raw mill, the raw materials are ground finer to ensure a high-quality blend.

Vertical mills and ball mills are applied in this stage, the vertical cement mill uses the pressure released from the drum to grind the passing material, and the cement ball mill relies on steel balls to grind the material.

The raw meal is finally transported to a homogenization yard for storage and further material mixing.

STEP3: Clinker production

A high-temperature treatment system consists of three steps: drying or preheating, and calcination.

Calcination is the core part of this process. The raw meal is continuously weighed and fed into a cyclone at the top of the preheater, where the material is heated by rising hot air, and the raw material is converted into clinker at 1450°C in the rotary kiln.

The clinker enters the grate cooler from the kiln head for thermal regeneration and cooling. The cooled clinker is then transported on a conveyor to the clinker silo for storage.

STEP4: Clinker grinding

The clinker is taken from the clinker silo and sent to the feed silo, where it is proportioned and mixed with gypsum and additives before entering the clinker mill.

In the clinker grinding process, clinker is ground together with slag powder and other raw materials to a fine powder, up to 5% gypsum or additional anhydrite is added to control the setting time of the cement, along with other compounds.

STEP5: Finished cement storage and packing

Finished cement is stored in huge concrete silos.

Cement can be shipped to customers in bulk in trucks or wagons or can be bagged by cement packing machines and sent in standard trucks.

Advantages Of Blast Furnace Slag Cement

  • Slag cement has good water retention, good plasticity, less bleeding, and good workability.
  • It can inhibit the dissolution of heavy metals such as high-valent chromium in concrete.
  • Reducing the heat of hydration is beneficial to prevent cracks caused by the internal temperature rise of mass concrete.
  • More ettringite crystals are produced to compensate for the drying shrinkage caused by too much fine powder in the concrete.
  • reduce the volume expansion and cracking of concrete caused by alkali-aggregate (sand, etc.) reaction, thereby reducing the production requirements for low-alkali cement.
  • The addition of slag powder can reduce the content of tricalcium aluminate and soluble calcium hydroxide in the cement, thus reducing the volume expansion of concrete due to sulfate attack.
  • reduce the color of cement. The more slag content, the lighter the color of cement and concrete, so slag cement can be used as a substitute for expensive white cement.
  • enhancing the anti-penetration ability of chloride ions and forming an anti-corrosion protective layer for steel bars, which is more suitable for coastal defense projects.

Uses Of Blast Furnace Slag Cement

It can be used for ordinary concrete, various high-grade concrete, high-performance concrete, and cement products to replace the amount of cement in a moderate amount to improve the durability of concrete and cement products in various harsh environments. Mixing with superfine powder such as slag improves the compactness of concrete and cement products, and its later strength is high, which reduces the cost of concrete and cement products

  • Applied for highways, airport runways, heavy-duty vehicle road engineering, etc.
  • It is used in high-strength, ultra-high-strength, high-performance concrete and prefabricated ready-mixed rods, pipes, large bridges and other industries of ordinary concrete, with high strength and smooth surface.
  • It is used in marine engineering, wharf, reservoir and tunnel engineering which are eroded by sea water.
    Basic engineering applied in various environments.

What is slag?

Slag, also known as granulized blast furnace slag, is a kind of glass materials formed by the blast furnace iron molten slag cold, too late to crystallized, its main group is divided into calcium oxide, silicon oxide and alumina, it has high potential activity, under the action of the activator, and water can be generated with hydraulic cementitious materials.