Preparation Of Ferronickel Research Articles

Effective utilization of Ni-Cr bearing composite burdens for high-Cr ferronickel preparation

In this paper, two types of Ni-Cr bearing composite burdens including SP1 (79% Ni-bearing sinter and 21% Cr-bearing oxide pellets) and SP2 (84% Ni-bearing sinter and 16% Cr-bearing pre-reduced pellets) were used for the more efficient preparation of high-Cr ferronickel. Based on the metallurgical performance characterization, thermodynamic analysis and smelting parameters optimization, the qualified high-Cr ferronickel were prepared by the utilization of the Ni-Cr bearing composite burdens. The recovery rates of iron, chromium and nickel exceed 95%, 90% and 98% whereas their grades are 85.56–85.88%, 7.82–8.02% and 1.59–1.62%, respectively. Compared with SP1, SP2 possesses lower smelting duration, which indicates the appropriate proportioning of Cr-bearing pre-reduced pellets is beneficial for the smelting process. The obtained high-Cr ferronickel consisting of (Fe, Cr)3C and (Fe, Cr)7C3 can be used as a low-cost substitute for the conventional raw materials of 200 or 300 series of stainless steel.

Efficient Utilization of Limonite Nickel Laterite to Prepare Ferronickel by the Selective Reduction Smelting Process

Ferronickel products obtained from the traditional process used to treat limonite nickel laterite usually assay very low-grade Ni, only 3–5% Ni due to the high Fe/Ni ratio of limonite nickel laterite. This paper describes an investigation conducted to upgrade limonite nickel laterites for the preparation of ferronickel by using selective reduction smelting technology. By means of thermodynamic calculations and smelting experiments, the smelting separation mechanism and the behavior of P and S removal in the smelting process, as well as the influence of smelting factors, have been systematically identified. The best production index of ferronickel is obtained under optimized conditions as follows: smelting the pre-reduced lumps at 1525 °C for 45 min with a basicity of 0.60, MgO/SiO2 ratio of 0.30, and nickel and iron metallization rate of 94.30% and 10.93%, respectively. The resulting ferronickel features a nickel and iron grade of 12.55% and 84.61% and a nickel and iron recovery of 85.65% and 10.87%, respectively. In addition, the content of S and P contained in ferronickel is only 0.11% and 0.0035%, respectively. The ferronickel obtained from the selective reduction smelting process is a fine material for the subsequent stainless steel smelting due to its high Ni grade and low content of impurities.

Migration and Aggregation Behavior of Nickel and Iron in Low Grade Laterite Ore with New Additives

This study focused on the preparation of high-grade ferronickel concentrate, the behavior of efficient migration and the polymerization of ferronickel particles during reduction roasting, by adding calcium fluoride and a ferronickel concentrate to low-grade laterite ore from Yunnan. The effects of temperature, holding time, reductant content, ferronickel concentrate content and magnetic field intensity on the preparation of the ferronickel concentrate were studied and the optimum conditions were determined as follows: 30% ferronickel concentrate (metal Ni-4.68%, metal Fe-45.0%), 8% coal, 7% calcium fluoride, reduction temperature of 1250 °C, reduction time of 60 min and the intensity of magnetic separation is 150 mT. The proportion of nickel and iron in ferronickel concentrate was 88.7% (metal Ni-8.62%, metal Fe-80.1%), and the recovery efficiency of nickel and iron are 98.8% and 82.4%, respectively. X-ray diffraction and scanning electron microscopy indicated that ferronickel-concentrate, as an activating agent, improved the aggregation effect of ferronickel particles. The efficient migration and polymerization of ferronickel particles in the ore significantly increased the size of the ferronickel particles with additives, therefore a high-grade ferronickel concentrate was prepared, and the reduction and recovery efficiency of laterite nickel ore was improved.

Coupled Preparation of Ferronickel and Cementitious Material from Laterite Nickel Ores.

Nickel slags can be produced through ferronickel preparation by the pyrometallurgical processing of laterite nickel ores; however, such techniques are underutilized at present, and serious environmental problems arise from the stockpiling of such nickel ores. In this study, a modification to the process of ferronickel preparation by the direct reduction of carbon bases in laterite nickel ores is proposed. The gangue from the ore is used as a raw material to prepare a cementitious material, with the main components of tricalcium silicate and tricalcium aluminate. By using FactSage software, thermodynamic calculations are performed to analyze the reduction of nickel and iron and the effect of reduction on the formation of tricalcium silicate and tricalcium aluminate. The feasibility of a coupled process to prepare ferronickel and cementitious materials by the direct reduction of laterite nickel ore and gangue calcination, respectively, is discussed under varying thermodynamic conditions. Different warming strategies are applied to experimentally verify the coupled reactions. The coupled preparation of ferronickel and cementitious materials with calcium silicate and calcium aluminate as the main phases in the same experimental process is realized.

Preparation of ferronickel from nickel laterite via coal-based reduction followed by magnetic separation

The sticking phenomenon between molten slag and refractory is one of the crucial problems when preparing ferronickel from laterite ore using rotary hearth furnace or rotary kiln processes. This study aims to ameliorate sticking problems by using silicon dioxide (SiO2) to adjust the melting degree of the briquette during reduction roasting. Thermodynamic analysis indicates that the melting temperature of the slag gradually increases with an increase in the SiO2 proportion (SiO2/(SiO2 + Al2O3 + MgO) mass ratio). Experimental validations also prove that the briquette retains its original shape when the SiO2 proportion is greater than 75wt%, and sticking problems are avoided during reduction. A ferronickel product with 8.33wt% Ni and 84.71wt% Fe was prepared via reductive roasting at 1500°C for 90 min with a SiO2 proportion of 75wt% and a C/O molar ratio of 1.0 followed by dry magnetic separation; the corresponding recoveries of Ni and Fe reached 75.70% and 77.97%, respectively. The microstructure and phase transformation of reduced briquette reveals that the aggregation and growth of ferronickel particles were not significantly affected after adding SiO2 to the reduction process.

Effect of Sodium Sulfate on Preparation of Ferronickel from Nickel Laterite by Carbothermal Reduction

Effect of Sodium Sulfate on Preparation of Ferronickel from Nickel Laterite by Carbothermal Reduction

Ferronickel preparation using Ni-Fe co-deposition process

Nucleation mechanism and technological process for Ni-Fe co-deposition with a relatively high Fe2+ concentration surrounded were described, and the effects of Fe2+ concentration, solution pH, temperature, and sodium dodecyl sulfonate concentration were investigated. Electrochemical experiments demonstrate that iron’s electrodeposition plays a leading role in the Ni-Fe co-deposition process, and the co-deposition nucleation mechanism accords with a progressive nucleation. Temperature increase does favor in increasing nickel content in the ferronickel (Ni-Fe co-deposition products), while Fe2+ concentration increase does not. When solution pH is higher than 3.5, nickel content in the ferronickel decreases with pH because of the hydrolysis of Fe2+. With the current density of 180 A/m2, Na2SO4 concentration of 100 g/L and Ni2+ concentration of 60 g/L, a smooth ferronickel deposit containing 96.21% Ni can be obtained under the conditions of temperature of 60 °C, Fe2+ concentration of 0.3 g/L, solution pH of 3 and sodium dodecyl sulfonate concentration of 40 mg/L.

Reductive roasting of nickel laterite ore with sodium sulfate for Fe-Ni production. Part I: Reduction/sulfidation characteristics

ABSTRACTThe selective reduction of nickel and adequate growth of ferronickel grains are imperative for efficient preparation of ferronickel from nickeliferous laterite ore via the process of direct reduction followed by magnetic separation. In Part I, reduction/sulfidation behaviors of a saprolitic laterite ore in the presence of sodium sulfate were investigated, with an emphasis on thermodynamic analysis, selective reduction/sulfidation ratios and kinetics. To separate the interactions between Ni and Fe, chemical titration analysis was adopted to determine the contents of various Ni and Fe species in the roasted pellets, and a modified equation to assay metallic iron content was proposed.