Air-cooled BFS Aggregates_CHC Resources Corp.

Raw materials and production processes

Limestone is added as a fluxing agent and coke as a reductant in iron-making in the blast furnace of a wholly integrated steel mill. The residual non-ferrous material after iron ore is reduced is blast furnace slag, which is in the form of molten slag under high heat. By passing the molten slag through high volume high pressure water sprays, CNS12223 blast furnace slag aggregates are produced. After being ground into powder, they are mainly utilized for use in construction. They can serve as a cement replacement in concrete. When they are air-cooled, they become air-cooled blast furnace slag aggregates.

When air-cooled blast furnace slag aggregates are crushed and screened to become BFS graded materials, different products can be manufactured according to engineering characteristics and material requirements, such as CNS11824 BFS coarse aggregates for concrete, CNS11890 BFS fine aggregates for concrete, CNS11827 BFS aggregates for roads, raw materials in cement plants, raw materials in mineral wool production for thermal insulation, etc.

Features

Blast furnace slag aggregates, which are grayish black in appearance, are similar to natural igneous rocks. Their size can be up to several meters big. They must be crushed and screened to become engineering materials. Because air is partially captured in the flowing and cooling processes in high temperature, their surface can be porous and uneven after they are cooled. They do not contain hazardous materials, such as heavy metals, dioxin, etc., owing to the smelting process in high temperature. The toxicity dissolution test results show the detected values are in full compliance with EPA’s regulatory requirements; in addition, the detected values of chromium, barium, and hexavalent chromium are lower than those of Type I Portland cement in the market.

The features of the engineering applications of blast furnace slag aggregates include good volume stability, potential cementitious properties, promotion of late strength or load-bearing capacity, shear strength and the angle of repose, and avoidance of alkali aggregate reaction in concrete. They are environmentally friendly materials which reduce the emissions of CO₂ and can be utilized to make structural concrete with ordinary strength, non-structural concrete (applied in manufacturing drain covers, tetrapods, curbs, high-pressure bricks, and permeable brick pavers), CLSM, etc.

Raw materials at a cement plant

BFS graded materials can partially replace natural limestone and clay in a cement plant. Their total alkali content (Na₂O+0.658K₂O) is lower than 0.6%, which demonstrates they are low-alkali raw materials and suitable in making cement which requires low alkali content.
BFS graded aggregates

BFS graded materials are potentially cementitious when used as the subbases/ base courses of roads whose strength and durability can be enhanced after the completion of construction. Furthermore, their maintenance costs can be reduced, construction is convenient, and the strength of the compactness of the subgrade is better than that of natural graded materials. The roads can be used right after the construction is completed. The following is the list of the domestic organizations which have utilized air-cooled blast furnace slag aggregates as the filling materials for the subbases/ base courses of roads in their engineering construction projects.
Basic furnace slag

Blast furnace slag aggregates can be applied for land leveling, gradation for temporary roads, filling for seawalls, buildings, or plant expansion projects. The following are many examples for their applications. The reason that blast furnace slag aggregates are applied to make river embankments is because the same mix proportion design can reduce the consumption of water-reducing admixtures and enhance workability. In addition, their compressive strength is higher than that of concrete with natural coarse aggregates, which demonstrates their potential cementitious property and effects in promoting the strength of concrete.