The main applications of blast-furnace slag are as follows: (1) Production of slag cement. Blast-furnace slag possesses latent hydraulic binding properties and, under the activation of cement clinker, lime, gypsum, and other activators, it can exhibit hydraulic binding performance, making it an excellent raw material for cement production. Slag can be used either as a cement admixture or, when processed into geotechnical drill rods, can even be made into cement without clinker. ① Slag silicate cement: The installation method for specialized drill bits used in coal mines in Fengtai County, Huainan, involves grinding together silicate cement clinker and blast-furnace slag, with the addition of 3% to 5% gypsum, either by simultaneous grinding followed by blending or by separate grinding and then thorough mixing. Slag silicate cement is commonly referred to as slag cement. When producing slag cement, the amount of blast-furnace slag added has little effect on the compressive strength of the cement but even less impact on tensile strength; thus, its proportion can range from 20% to 85% by weight of the cement. This makes it highly advantageous for improving cement quality and reducing cement production costs. ② Gypsum-slag cement: This is a hydraulic binding material obtained by grinding dry blast-furnace slag and gypsum together with silicate cement clinker or lime at specific proportions, either by simultaneous grinding and blending or by separate grinding followed by uniform mixing. In the preparation of gypsum-slag cement, blast-furnace slag is the primary raw material, typically accounting for about 80% of the mix. This type of gypsum-slag cement has low production costs and exhibits good resistance to sulfate attack and permeability, making it suitable for hydraulic structures made of concrete as well as various precast blocks. ③ Lime-slag cement: This is a hydraulic binding material produced by grinding together dry blast-furnace slag, quicklime or hydrated lime, and natural gypsum (at less than 5%) according to appropriate proportions. The lime content generally ranges from 10% to 30%; its role is to activate the reactive components in the slag, forming calcium aluminate hydrate and calcium silicate hydrate. If the lime content is too low, the reactive components in the slag cannot be fully activated; if it’s too high, the cement may set abnormally and its strength will decline. Lime-slag cement can be used for various steam-cured concrete precast products, as well as for unreinforced concrete and construction mortars in underground, road, and other environments—whether in water or on land—in Huainan Fengtai County, where specialized drill bits for coal mines are installed. (2) Production of slag bricks and wet-milled slag concrete products. ① Slag bricks: Bricks made by adding a certain amount of cement and other binding materials to slag, followed by mixing, molding, and steam curing, are called slag bricks. By using 87% to 92% slag, 5% to 8% cement, and 3% to 5% water mixed together, the bricks produced by companies such as Yanggu Jinxing Mining Tools Co., Ltd.—including blast-furnace drill bits, wholesale blast-furnace drill bits, open-hole blast-furnace drill bits, opening machine drill bits, blast-furnace drill manufacturers, cross-bit drills, ball-tooth drills, air drills, iron-mouth opening drills—can achieve a strength of around 10 MPa and are suitable for both ordinary building construction and underground structures. Additionally, by grinding blast-furnace slag into slag powder and mixing it at a weight ratio of 40% slag powder and 60% slag, adding water, molding, and then autoclaving under a steam pressure of 100–110 MPa for 6 hours, bricks with significantly higher compressive strength can also be produced. ② Wet-milled slag concrete: This is a type of concrete made primarily from slag. Its manufacturing process involves placing slag and activators (cement, lime, and gypsum) into a roller mill, adding water, and grinding them into a mortar before mixing with coarse aggregates. The physical and mechanical properties of wet-milled slag concrete—including tensile strength, elastic modulus, fatigue resistance, and bond strength with reinforcing bars—are similar to those of ordinary concrete. Its main advantage lies in its excellent resistance to water penetration, allowing it to produce waterproof concrete with outstanding impermeability; it also has excellent heat resistance, making it suitable for thermal engineering applications where operating temperatures are below 600°C, and enabling the production of concrete with strengths up to 50 MPa. This type of concrete is ideally suited for small-scale concrete prefabrication plants but is not recommended for on-site casting. (3) Use as thermal insulation filler: It can replace diatomaceous earth as a thermal insulation filler, thereby reducing costs. (4) Production of slag micro-powder: Blast-furnace slag, after ultrafine grinding, can serve as the primary raw material for producing slag micro-powder.