Study On Carbothermal Reduction-leaching Process Of Rare Polymetallic Mixed Concentrate

This paper,by using the reduction roasting-hydrochloric acid leaching process,will be undressed ore through magnetic separation-gravity separation-high intensity magnetic separation concentrate and nonmagnetic mixed concentrate,mixed minerals through grinding machine,the level of shaking table selection and hybrid polymetallic ore concentrate as raw materials for the main research of this experiment,the first carbon roasting,through changing the variable of roasting and thus to find the most suitable for roasting conditions,And through thermodynamic analysis software to establish the reaction process temperature and Gibbs free energy changes of the relationship,the use of scanning electron microscope for microscopic observation,through the energy spectrum analysis of chemical element composition analysis,thus to determine the mixed concentrate in the process of reduction roasting element migration and phase changes;Then the calcined ore was naturally cooled and leached by hydrochloric acid.The mass fraction and chemical composition of valuable elements in the leached solution and leached residue were detected by ICP,XRD and other analytical equipment.In the process of roasting,the ore containing Fe element is reduced by carbon under the condition of roasting at 500-1100?.When it reaches about 1000?,the metallization rate of Fe is the highest.At the same time,silicate is separated from the silicate-wrapped Fe element material.Due to the action of physical and chemical reaction,the Fe in the original niobite is reduced to form a metal element,so that the separation of Fe and niobium,the appearance of Nb oxide,so as to achieve the purpose of Fe-Nb separation.A part of the mixed concentrate containing rare earth minerals(such as fluorobescerite)reacts;Other metal elements associated with the original Zr element were gradually separated to form a relatively pure Zr Si O4.With the increase of temperature,the reduced elemental Fe reacts with O₂in the air to form Fe₃O₄at the temperature of 1100-1500?.A small part of the reduced elemental Fe does not escape from silicate but forms Fe-Si phase,while a part produces Fe-C phase.Nb-containing minerals gradually form relatively stable oxides,a small part of which will react with C to produce carbides of Nb;Most of the rare earth minerals are decomposed to form rare earth oxides,some of which form rare earth carbides.Zr Si O₄containing Zr is decomposed into granular Zr O₂and Si O_2,and the resulting molten Si O₂forms a new phase with other metals or metal oxides.Above 1500°C,the reaction continues to form new and more complex phases,such as Zr₄Fe₄Si₇and other substances formed at 1800°C.Therefore,the roasting ore produced under the condition of reduction roasting temperature of 1000?and carbon content of C/O=1.5 was selected as the raw material for leaching.In the process of hydrochloric acid leaching,by controlling the concentration of hydrochloric acid,acid leaching time,solid-liquid ratio and acid leaching temperature and other variables,the technological parameters with the highest metal leaching effect are determined as follows:concentration of hydrochloric acid is 6mol/L,acid leaching time is3h,and solid-liquid ratio is 1:6.The acid leaching temperature is 40?,in which theleaching rate of Fe is more than 95%,the leaching rate of rare earth is more than 60%and that of Mn is more than 60%.After the secondary leaching of the primary leaching residue,the leaching rate of Fe reaches more than 98%.The leaching rate of rare earth reaches more than 70%,and the leaching rate of Mn is relatively low,and the leaching rate is increased by 5%.In the leaching residue,Zr O₂,Nb-containing oxides and Ti-containing oxides achieve the purpose of enrichment,and the required valuable metals are successfully separated,which lays a foundation for the subsequent extraction process.