Effect of Basicity on the Microstructure of Sinter and Its Application Based on Deep Learning

The influence of the evolution rule of basicity (0.6∼2.4) on the mineral composition and microstructure of sinter is studied by using a polarizing microscope, and the comprehensive application analysis of the drum index, vertical sintering speed, and yield of sinter shows that, over the course of an increase in basicity (0.6∼1.0), the mineral structure changed from the original porphyritic-granular structure to a porphyritic structure. At the same time, there was no calcium ferrite phase in the bonding phase at a basicity of less than 1.0; therefore, the downward trend of the three indicators is obvious. When the basicity was further increased to approximately 1.6, the main structure of the mineral phase changed from a corrosion structure to an interweaving corrosion structure. Because of the existence of a porphyritic-granular structure, the structure of the mineral phase was extremely inhomogeneous and most complex near the basicity of 1.6; although a small amount of calcium ferrite displayed an acicular structure, the drum index appeared to show a very low value. With an increase in basicity to 2.0, the mineral phase structure was dominated by an interweaving corrosion structure with a uniform framework, and the content of calcium ferrite reached the highest value. Moreover, a clear acicular structure developed, and the drum index also increased to the highest value. At a basicity of more than 2.0, a mineral structure began to appear and the corrosion, porphyritic-granular structure, and the drum index also showed a slightly declining trend. Therefore, in the actual production process, basicity should be avoided as far as possible at around 1.0 and 1.6 and it should be controlled at around 2.0. At the same time, based on the mineral facies data set of this paper, the convolutional neural network is used to carry out a simple prediction model experiment on the basicity corresponding to the mineral facies photos, and the effect is quite good, which provides a new idea and method for the follow-up study of mineral facies.

Study on Sintering Characteristics of Ultra-Poor Vanadium-Titanium Magnetite

Artificial rich ore for blast furnace use can be produced by sintering ultra-poor vanadium-titanium magnetite (PVTM) with a high-grade iron concentrate. Here, acid (R = 0.33, 0.50), self-fluxing (R = 1.10), and high-basicity (R = 2.60) PVTM sinters were produced in a sinter pot. Their performances were determined using the comprehensive index. The microstructures of the PVTM sinter were observed by metallographic microscope and scanning electron microscopy equipped with an energy dispersion spectrum (SEM-EDS). The results suggest that the acid PVTM sinter had a low flame front speed, low productivity, an uneven size distribution, and poor softening properties. It did have a high tumble index (TI) and low-temperature reduction disintegration index (RDI). The self-fluxing PVTM sinter had the worst performance (TI, RDI, reducibility index (RI)), while the high-basicity PVTM sinter had the highest flame front speed, highest productivity, a reasonable size distribution, excellent softening properties, and satisfactory TI and RDI values. The main consolidation form of the acid sinter was crystal stock, the main bonding phase of the self-fluxing sinter was silicate, and the main bonding phase of the high-basicity sinter was silico-ferrite of calcium and aluminum (SFCA). The comprehensive index values (from high to low) were the high-basicity (R = 2.60), acid (R = 0.50), natural acid (R = 0.33), and self-fluxing (R = 1.10) PVTM sinters. When the production capacity of the acid pellet was in shortage, the acid PVTM sinter (R = 0.50) could be produced by the surplus from the sinter plant. This replaced a part of the acid pellet and the burden structural model of the blast furnace smelting vanadium so the titanium burden could adopt a ‘high-basicity PVTM sinter + acid V-Ti pellet + acid (R = 0.50) PVTM sinter’.

Effect of B2O3 Content on the Sintering Basic Characteristics of Mixed Ore Powder of Vanadium-Titanium Magnetite and Hematite

The sintering basic characteristics of iron ore play a key role in the process of sintering. In this study, the effects of B2O3 on the assimilation characteristics, softening temperature, fluidity of liquid phase, compressive strength of bonding phase, and microstructure of the mixed fine powder of hematite and vanadium-titanium magnetite (H-VTM) are studied. Results show that B2O3 content from 0%–5% (wt%) could improve the assimilation characteristics of the H-VTM and increase the amount of the liquid phase. The liquidity of the bonding phase index (LBPI) of the H-VTM increases from 3.7 to 24.2. When B2O3 content exceeds 2%, the diameter of the pore in the H-VTM sintered samples enlarges. However, the compressive strength gradually decreases. Boron and calcium-magnesium-aluminium elements are abundant in the bonding phase, which can reduce the formation of calcium silicate and perovskite in H-VTM sintered samples.

Effect of Ruthenium on Microstructure and Properties of WC- (W, Ti, Ta) C-Co Cemented Carbide

Two different ruthenium content (0.5%, 1.0%) of WC - (W, Ti, Ta) C - Co cemented carbide were prepared by conventional cemented carbide production process. The results showed that adding ruthenium powder can improve the microstructure of alloy compared with excluding ruthenium carbide. The microstructure of alloy with ruthenium addition had uniform structure with less coarse grain.The addition of ruthenium could obviously promote the transverse rupture strength of WC - (W, Ti, Ta) C-Co cemented carbide, and when the adding amount was 1.0%, transverse rupture strength increased by 30%. The addition of ruthenium slightly increased the hardness of the alloy. The results of Scanning electron microscopy and spectrum analysis showed that ruthenium mainly existed in the bonding phase Co. The cutting test showed that the alloy with Ru had better wear resistance.