Study On Regulating Micritization For Preparation Glass Ceramics With Massive Yellow Phosphorus Slag

The yellow phosphorus slag is a solid waste in the production of yellow phosphorus with electric furnace process. According to different cooling ways, there are water quenching and natural cooling of yellow phosphorus slag. Water quench has become a common method to treat molten yellow phosphorus slag in our country.The slag mainly used in cement industry, silicon-calcium fertilizer and subgrade materials etc, which has low additional valve of product. There are many similarities between massive slag and molten yellow phosphorus slag. This paper researches preparation of CaO-Al2O3-SiO2 system glass ceramics with massive yellow phosphorus slag, which uses the melt wetting method. We optimized research of the raw materials proportion, and researched heat treatment system of nucleation temperature, nucleation time, crystallization temperature, crystallization time and so on, by physicochemical properties and microstructure analysis. These above investigations provide theoretical foundation for the research on efficient utilization of yellow phosphorus furnace slag in molten state.According to CaO-Al2O3-SiO2 System, we determine wollastonite as the dominant crystalline phase of glass ceramics. There are 55～78wt% slag,19-38wt% SiO2 auxiliary materials,2.4～11wt% Al2O3 auxiliary materials, in the raw materials proportion of basic glass. And we set 6 experiment programs of the raw materials proportion. The 1# raw materials proportion, slag:SiO2:Al2O3= 63.4:33.8:2.8.The 2# raw materials proportion, slag:SiO2:Al2O3=51.7:37.5:10.8. The 3# raw materials proportion, slag:SiO2:Al2O3= 77.7:19.4:2.9. The 4# raw materials proportion, slag:SiO2:Al2O3= 56.6:35.5:7.9. The 5# raw materials proportion, slag:SiO2:Al2O3= 61.2:32.7:6.1. And the 6# raw materials proportion, slag:SiO2:Al2O3= 62.4:30.3:7.3. The 1" to 6# raw materials are fully separate mixed, melting at 1300-1400℃ to make basic glass.1# raw materials proportion is easy to crystallize from DSC diagram of the basic glass. It uses two-step process heat treatment system. The dominant crystalline phase of glass ceramics is wollastonite from 1# basic glass by heat treatment. And the glass ceramics is white. It hasn’t crack. We select 1# for the best raw materials proportion of basic glass in the study.On the Basis of 1# raw materials proportion,3.37% Cr2O3 is added to 7# for nucleation agent. DSC diagram of 7# basic glass has no pronounced exothermic peak, which is difficult to crystallize. Trace components of slag are used as composite nucleation agents. And we don’t add other nucleation agent to the raw materials proportion of basic glass in this paper.Preheating the forming die with metal below 100℃, rapid casting forming at the furnace mouth, treating with annealing to make basic glass. These above ways obtain basic glass with small residual stresses and no crack, and improve efficiency of forming.The transition temperature of sample 1# is 717℃ from DSC diagram of 1# basic glass. Setting nucleation temperature is 720℃～870℃, and nucleation time is 1-3h. The crystalline exothermic peak of sample 1# is 980℃ from DSC diagram of 1# basic glass. Setting crystallization temperature is 980℃～1100℃, and crystallization time is 1～3h. We did the single factor experiment of nucleation temperature, nucleation time, crystallization temperature and crystallization time. The paper sets contrastive study on quick heating, slow heating speed and suitable heating speed, from 1.5～15℃/min of nucleation heating rate and 2.5～11℃/min of crystallization heating rate. We define suitable heat treatment system by analysis of XRD, crystallinity calculation, Mons’hardness scale, metallurgical microscope and SEM. These are 740℃ nucleation temperature,2 hours nucleation time, 3.5℃/min of nucleation heating rate,1050℃ crystallization temperature,2 hours crystallization time and 3.6℃/min of crystallization heating rate. The dominant crystalline phase of glass ceramics is wollastonite by suitable heat treatment system. The crystals are oval with great quantity, fine particle and uniform distribution. The sample has high-crystallinity, full-grown, superior Mons’hardness scale of sample performance.