## 1 Introduction  
As solid industrial waste, the inventories of blast furnace slag (BFS), manganese tailing slag (MTS), water-quenched manganese slag (WQMS) and desulfurization gypsum (DG) gradually increase with time. It not only occupies a large amount of land but also contains pollutants such as acid radical ions and heavy metal ions, which will cause huge pollution to air, water and soil during the stacking process. Therefore, how to recycle these solid wastes with high efficiency and high added value has become an urgent problem to be solved.  
BFS is a solid waste produced in the process of blast furnace ironmaking. It mainly contains CaO, SiO\({}_{2}\), Al\({}_{2}\)O\({}_{3}\) and other oxides. The total amount of these oxides is generally more than 90%, which has a high potential activity [1]. A large number of studies have shown that BFS is the most common solid waste material for preparing composite micronized powder. Replacing a part of ordinary Portland cement (OPC) with BFS can not only reduce costs but also improve the durability and long-term mechanical properties of concrete [2]. [PERSON] studied the influence of adding slag powder and fly ash to concrete and found that the workability and mechanical properties of concrete have been improved [3]. [PERSON] also used the composite powder prepared with slag and fly ash in a ratio of 1:1 to replace 30% of the cement, which improved the mechanical properties of concrete [4].  
MTS is an industrial solid waste produced after manganese ore beneficiation, which mainly contains minerals such as dihydrate gypsum, quartz and hydrated calcium silicate. MTS can replace a part of cement to prepare concrete, which can change the pore structure of concrete and improve the impermeability, frost resistance and durability of concrete [5; 6]. [PERSON] prepared aerated concrete with an excellent performance by mixing lime, gypsum, cement, MTS and aluminum powder in a certain ratio [7].  
WQMS is a kind of slag waste formed by water quenching in the high-temperature melting state during the smelting process of manganese ore. The main mineral composition is mainly glass phase (about 85%), which contains active or potential hydrosetting and pozzolanic substances, such as dicalcium silicate and magnesium rose pyroxene [8]. Therefore, WQMS can be used as a concrete admixture and a cement admixture. [PERSON]'s research found that WQMS plays an important role in improving the durability of concrete and believes that it can be used as mineral powder in offshore and marine environment concrete projects [9].  
DG is an industrial by-product obtained after wet flue gas desulfurization. The main component is CaSO\({}_{4}\) 2H\({}_{2}\)O. At present, the annual output of desulfurization gypsum in China has reached 80 million tons [10]. DG can be used as a cement retarder and can reduce the drying shrinkage of cementitious materials [11]. [PERSON] et al. found that compared with natural gypsum, the addition of DG not only prolongs the setting time of cement but also increases the mechanical properties of cement [12].  
Solid-waste-based composite micronized powder is a kind of ultra-fine powder with small particle size and high activity prepared from industrial solid waste. It has the characteristics of low hydration heat, high activity and environmental protection. Based on the above contents, it is shown that BFS, MTS, WQMS and DG can be used to prepare composite micronized powder for cement and concrete. Using the characteristics of these solid wastes to prepare composite micronized powder with performance meeting the requirements of S95 grade mineral powder through complementary advantages can not only benefit society and improve the ecology but also have significant economic benefits.