Cement knowledge Complete book cement basic knowledge

12. White Portland cement: White cement made from Portland cement clinker with low iron oxide content, adding an appropriate amount of gypsum and grinding fine.

13, road Portland cement: By road Portland cement skilled, 0%~10% active mixture material and an appropriate amount of gypsum ground fine made of hydraulic cementing material, known as road Portland cement, (referred to as road cement).

14, masonry cement: by active mixed materials, adding an appropriate amount of Portland cement clinker and gypsum, grinding to make a low-grade cement mainly used for masonry mortar.

15, oil well cement: by the appropriate mineral composition of Portland cement clinker, an appropriate amount of gypsum and mixed materials, such as ground fine made for oil and gas well cementing engineering under certain well temperature conditions.

16, gypsum slag cement: granulated blast furnace slag as the main component material, adding an appropriate amount of gypsum, Portland cement clinker or lime grinding made of cement.

6. Types and functions of cement kilns

At present, there are two main categories of cement kilns, one is the kiln body lying down (slightly inclined), and can do rotary movement called rotary kiln (also known as rotary kiln); The other type of kiln is called shaft kiln which is upright and does not rotate. The type of cement rotary kiln is characterized:

Cement industry in the development process of different production methods and different types of rotary kiln, according to the raw material preparation method can be divided into dry production and wet production, and the production method is suitable for the rotary kiln is divided into dry rotary kiln and wet rotary kiln two categories. Because of the different heat exchange devices in the kiln, it can be divided into different types of kilns. The classification of rotary kilns is roughly as follows:

1, the type of wet rotary kiln:

Cement kilns used in wet production are called wet kilns, and wet production is to make raw materials into slurry with a water content of 32% to 40%. Due to the preparation of mud with fluidity, the raw materials are mixed well, the raw material composition is uniform, so that the sintered clinker quality is high, which is the main advantage of wet production.

2, the type of dry rotary kiln:

The advantages and disadvantages of dry rotary kiln are opposite to those of wet rotary kiln. The dry method makes raw materials into raw dry powder, and the moisture is generally less than 1%, so it reduces the heat required to evaporate water than the wet method. Because of the high exhaust gas temperature, the heat consumption of the hollow kiln is not low. Dry production produces dry powder from raw material, which has a lower fluidity than mud. So the raw materials are not mixed well and the ingredients are not uniform.

7, the type of cement shaft kiln is characteristic

There are two types of shaft kilns currently used in China: ordinary shaft kilns and mechanical shaft kilns. Ordinary shaft kiln is manual feeding and manual unloading or mechanical feeding, manual unloading; Mechanical shaft kiln is mechanical feeding and mechanical unloading. Mechanical shaft kiln is continuously operated, and its production, quality and labor productivity are higher than ordinary shaft kiln. According to the requirements of building materials technology policy, small cement plants apply mechanized shaft kilns to gradually replace ordinary shaft kilns.

Quality control and standards in cement production

The quality management of cement production mainly has two aspects: on the one hand, it is to control the normal operation of the main equipment - kiln and mill within the control range of the index; On the other hand, it is to manage the quantity and quality of raw materials, coal, raw materials, clinker and cement in various warehouses, master the incoming and outgoing warehouses, and ensure the normal operation of production. To determine the quality control points and control indicators is a very important work, we must start from the specific situation of the factory process and equipment, develop a reasonable and feasible program, in order to better guide production.

Nine, China's cement standard system, revision of the main content

There are two main changes in China's new cement standard compared with the old standard: First, GB/T 17671-1999 "cement mortar strength test method (ISO method)" instead of the current GB177-85 "cement mortar strength test Method"; The second is to revise the six general cement standards based on ISO strength.

GB/T 17671-1999 "Cement mortar strength Test Method (ISO method)" standard formulation GB/T 17671-1999 is equivalent to the international standard ISO 679-1989 developed in China, released on February 8, 1999, effective from May 1, 1999. GB/T 17671-1999 and GB177-85 belong to the "soft training method" of testing the strength of cement mortar, that is, the use of plastic sand, 4X4X160m prism test, the test body is first tested for bending strength, and the two halves of the broken test body are then tested for compressive strength. The core difference between the two is that the composition of mortar is different, the water-cement ratio used by the ISO method is moderate, the lime sand ratio is moderate, especially the gradation standard sand is used, so the strength value obtained by the ISO method is closer to the use of cement in concrete than the GB-177 method.