Current status of iron ore tailings building materials utilization

The comprehensive utilization technology of tailings has been promoted abroad and achieved good results. At present, the use of high silicon iron tailings supplies mainly in high-grade cement, building ceramics, unburned bricks and sintered, high-grade decorative materials, glass, granite.

First, high-grade cement

The main raw materials are iron tailings grade cement, limestone, coal ash powder and a sulfuric acid residue, tailings amount of iron can reach about 15%, wherein the ferrous material than the n - residue can be sulfated according to iron in iron tailing The content is adjusted to be used when the iron oxide content reaches the required time base. The raw materials are made through processes such as crushing and grinding, batching, stirring and firing, and their performance fully meets the requirements.

Taking appropriate measures, the new dry process cement production line can completely replace the traditional silicon and iron materials with iron tailings, and the clinker produced is of good quality, which can stably produce ordinary 52.5[R] high-strength grade cement and tons of clinker. The cost is reduced by nearly 5 yuan. However, due to the large water content of the iron tailings powder, forced feeding should be adopted to ensure smooth feeding; iron tailings ingredients may have slight crusts, and the kiln tail pre-decomposition system needs to strengthen anti-blocking measures, and more air bubbles are provided. Calcination system; the effect of tailings waste rock in winter production is better.

The successful application of tailings in the new dry clinker production line has found new ways for its extensive utilization, solved environmental pollution, improved the ecological environment, and has enormous economic, social and environmental benefits.

Second, free brick

Tailings non-burning brick is the main raw material, the amount can be up to 70%, adding cement, aggregate, additive, the body is formed into vibration molding, curing temperature is 20 ° C, curing for 10, 28 days. In the case of reasonable aggregate ratio, the coarse-grained sand in iron tailings can be used instead. According to the role of tailings in the material, it can be divided into three kinds of utilization forms: 1) It is only used as aggregate, mainly in the structure of products. As a supporting skeleton, the hydration synthesis reaction only occurs in the range of about 3 μm on the surface of the particles; 2) as a binder (commonly called fine tailings), mainly by chemical reaction to synthesize a new gel or Crystalline minerals connect the body to cement the aggregate into a whole; 3) use natural grain grade tailings sand, directly mixed with alkaline activator. The combination is achieved by relying on the interface reaction. The production process is shown in Figure 1.

Figure 1 Production process of unburned brick

The steam-free brick is a cemented tailings building material, which means that the tailings particles are combined into a whole by a cementing material under normal temperature or not higher than 100 °C. The difference from the autoclaved brick is that it does not use autoclaving, but uses normal temperature curing. The advantage is that it reduces equipment investment and reduces production cost, and has more practical significance for accelerating the promotion and application of such building materials.

Third, concrete small hollow block

The main raw materials for the production of concrete blocks are iron tailings, fly ash, coarse aggregates and cement. The raw materials are made by processes such as metering, mixing, forming and curing. In concrete blocks, fly ash is both admixture and fine aggregate, and the amount of iron tailings is 45%.

In addition to the load-bearing structure widely used in residential buildings and the envelope structure of industrial and civil buildings, building blocks can also be used for decoration, municipal construction and water conservancy projects, urban garden buildings, etc.

Building blocks are as good as other products, and their quality is closely related to their promotion and application. The current problems of block quality are mainly manifested in poor appearance quality, large geometric dimensional deviation, unstable block strength, and impermeability. To accelerate the development of the construction industry. It is necessary to improve the quality of the block products as soon as possible, and to deeply study the thermal insulation performance of the blocks so that they can meet the requirements of energy-saving buildings and reduce the thickness of the walls.

Fourth, glass-ceramic

Glass-ceramic, also known as glass-ceramic, is a material in which the microcrystals and the glass phase are uniformly distributed by the crystallization of the base glass. Glass-ceramics differ from ordinary glass in that they have a crystalline structure, and the difference from ceramic materials is that their crystal structure is much finer.

Production Tailings Tailings iron glass matrix material, quartz _{sand, CaCO 3, A1 2 O 3} , MgO, Na 2 CO 3, K 2 CO 3, BaCO 3, borax and the like, wherein an amount of up to tailings 60%, the sample product is formed by a water quenching process (see Figure 2).

Figure 2 Water quenching process for producing glass-ceramics

The heat treatment process is: nucleation temperature 770 ° C, holding time 60 minutes; crystallization temperature 870 ° C, holding time 60 minutes, heating rate 5 ° C / min.