Significant influence of self-possessed moisture of limonitic nickel laterite on sintering performance and its action mechanism

In consideration of the abundant moisture of limonitic nickel laterite mined, it is essential to determine whether the self-possessed moisture of limonitic nickel laterite after pre-dried is appropriate for sintering. Thus, based on the characterization of limonitic nickel laterite, the influence of its self-possessed moisture on sintering performance was expounded by sinter pot tests and the relevant mechanism was revealed by the systematical analyses of the granulation properties of sinter mixture, thermodynamic conditions during sintering and mineralogy of product sinter. The results indicate that the self-possessed moisture of limonitic nickel laterite indeed has significant influence on its sintering performance. At the optimum self-possessed moisture of 21 mass%, sinter indices are relatively better with tumble index, productivity and solid fuel rate of 48.87%, 1.04 t m−2 h−1 and 136.52 kg t−1, respectively, due to the superior granulation properties of sinter mixture and thermodynamic conditions during sintering, relatively large amount of silico-ferrite of calcium and alumina and tighter sinter microstructure. However, sintering performance of limonitic nickel laterite is still much poorer than that of ordinary iron ores. It is feasible to strengthen limonitic nickel laterite sintering by inhibiting the over-fast sintering speed and improving the thermodynamic conditions during sintering.

Increasing the efficiency of blast-furnace smelting by improving the quality of iron ore materials

It is noted in the work that when mastering the technology of pulverized coal injection (PUT) at the metallurgical enterprises of Ukraine, it is necessary to intensify work, including research, in the direction of improving the quality characteristics of the sinter, the stability of its chemical composition and strength parameters. The analysis of the quality of iron ore raw materials used in sintering production in Ukraine and foreign countries is carried out. The requirements of international and domestic standards for the quality of raw materials and fuels, providing for the injection of large quantities of firearms into the furnace, are given. A methodology for determining the quality of raw materials developed in the HMI is described. The results of a study of the quality of iron ore raw materials according to the developed method are presented. Based on the analysis of the results of the research, requirements were developed for the quality of granular iron ore wastes and their rational amount in the composition of the sinter charge, and the process for the production of granules was developed. Recommendations have been developed on the use in the sinter mixture of a part of the granular components of secondary waste, which allowed to increase the content of secondary resources in the mixture. As a result, the chemical composition of the sinter was stabilized, its strength was improved, the yield of sinter of the second grade was reduced, the removal of blast furnace dust and coke consumption were reduced. Improving the quality of the sinter and the rational distribution of charge materials over the cross-section of the top of the blast furnace allows for self-renewal of the protective skull, to reduce the removal of top dust by 4.3 kg / t of cast iron, and to reduce coke consumption by 19.6 kg / t of cast iron. The developed measures make it possible to increase the competitiveness of products, even at the additional cost of preparing the sinter mixture for sintering.

The Sinter Mixture Moisture Control System Based on Fuzzy PID Controller

Because the sinter mixture moisture control system has time-varying, nonlinear and time-delay characteristics, it is difficult to establish its precise mathematical model. According to the defects that the conventional PID control in the fixed parameter is difficult to guarantee the system performance, this paper proposed the parameter self-tuning fuzzy PID controller which is used to the system. Based on the sintering furnace structural features and control performance requirements, the PID parameters are set by fuzzy logic reasoning. The actual operation results proved that the parameter self-tuning fuzzy PID controller improved more obviously the system performance than the original PID controller, and stabilized the sinter mixture moisture, and improved the sintering production condition and promoted the production capacity.

Method and Technique of Grade Recovery and Cascade Utilization (GRUC) Based on Sintering and Cooling Integration

The key problems and causes of recovery and Utilization of sintering waste heat were analyzed firstly, on the basis of sintering and cooling integration , the method and technique of grade recovery and cascade utilization (GRUC) was put forward according to the first and second laws of thermodynamics. The waste heat was recovered in grades according to the quality firstly, and then different qualities of residual heat recovered were utilized in cascades. The higher temperature part of sinter cooling waste gas was used for power recovery, the medium temperature part was used for direct thermal utilizations, such as drying and preheating of sinter mixture, combustion supporting for ignition, hot air sintering and so on, and the lower temperature part was used for absorption refrigeration. Last, a 360m2 sintering machine of JTC was put forward as an example to validate economic feasibility of the process.

Improving the Granulating and Sintering Performance by Pretreating Concentrates Using Extrusion Machine

In this paper, the pretreatment of concentrates by extrusion machine was present to improve the granulation of blends comprising some 30% iron ore concentrates and enhance the sintering performance. It is shown that by pretreatment of fine concentrates through extrusion machine, the content of +3mm fractions of granulation mixture and sinter mixture permeability are elevated by 10% and 35%, respectively. In the meantime, an increase in sinter productivity from 1.51 to 1.62t.m-2.h-1 is attainted in pot tests with similar sinter tumble index and at lower coke rate. The mechanism of the pretreatment of concentrates process to improve sintering performance of fine iron ore concentrates was demonstrated by mineralogy that better permeability help form more calcium ferrite and good microstructure of sinter, further proven by the better metallurgical performance of sinter.