In this study, to better understand the influence of hydrothermal processes on ore metal accumulation in bottom sediments, we examined distribution of Fe, Mn, Cu, Zn, As, and Pb in core of metalliferous sediments from the Pobeda hydrothermal cluster, and in core of non-mineralized (background) carbonate sediments (located 69 km northwards). Mechanisms of Fe, Mn, Cu, and Zn accumulation in sediments (12 samples) were evaluated based on sequential extraction of geochemical fractions, including a conditional mobile (F-1, exchangeable complex; F-2, authigenic Fe-Mn oxyhydroxides and associated metals; F-3, metals bound to organic matter/sulfides), and residual (F-4), fixed in crystalline lattices ones. The element contents were determined by the XRF and AAS methods, total carbon (TC) and total organic carbon (TOC) were determined using a Shimadzu TOC-L-CPN. Mineral composition and maps of element distribution in sediment components were obtained using the XRD and SEM-micro-X-ray spectrometry methods, respectively. In metalliferous sediments, according to our data, the major Fe mineral phase was goethite FeOOH (37–44% on a carbonate-free basis, cfb). In the metalliferous core, average contents (cfb), of Fe and Mn were 32.1% and 0.29%, whereas those of Cu, Zn, Pb, and As, were 0.74%, 0.27%, 0.03%, and 0.02%, respectively. Metalliferous sediments are enriched in Fe, Cu, Zn, Pb, and As, relatively to background ones. The exception was Mn, for which no increased accumulation in metalliferous core was recorded. Essential mass of Fe (up to 70% of total content) was represented by the residual fraction composed of crystallized goethite, aluminosilicates, the minerals derived from bedrock destruction processes mineral debris. Among geochemically mobile fractions, to 80% Fe of the (F-1 + F-2 + F-3) sum was determined in the form of F-2, authigenic oxyhydroxides. The same fraction was a predominant host for Mn in both metalliferous and background sediments (to 85%). With these Fe and Mn fractions, a major portion of Cu, Zn, and Pb was associated, while a less their amount was found in sulfide/organic fraction. In the metalliferous sediment core, maximal concentrations of metals and their geochemically mobile fractions were recorded in the deeper core sediment layers, an observation that might be attributed to influence of hydrothermal diffused fluids. Our data suggested that ore metals are mostly accumulated in sediment cores in their contact zone with the underlying serpentinized peridotites.

No abstract

No abstract

Pachuca tanks are widely used in the uranium industry for ore redistribution [1, 2]. Just as for all mixing apparatus, they are inefficient. Continuous extraction of uranium from ore pulp, sorption extraction from the liquid phase of the pulp, and washing of sorbents requires at least 4-10 Pachuca tanks.We have developed a highly efficient technology for sorption extraction of uranium from ore pulps, washing sorbent from pulp and the regenerating solution [3], as well as sorbent regeneration in the counterflow regime in displacement apparatus -pulsatioual columns. A series of physical-chemical investigations of these processes,' which are necessary for calculating pulsational equipment, was carried out. First, the equilibrium and kinetic characteristics of the processes were measured, and the density of the reagents, rate of settling of the sorbent and sand fraction in the systems investigated, separation of the pulp and others were determined. The hydrodynamics of the sorption processes, performed in the pulp-sorbent system, depends on the aggregate stability of the dispersion systems. A disruption of this stability can result either in the formation of macrophases, which will give rise to intense separation of the system, or development of the spatial network-structure, i.e., transition of a freely dispersed system into a coupled dispersed system, in which the coupling forces between the particles are strong enough to withstand the thermal motion and external actions, and this will increase sharply the viscosity of the system. Therefore, investigation of the laws of structure formation in dispersed systems and investigation of the mechanical properties of structured systems are important in hydrodynamic processes, specifically, accompanying leaching and sorption of uranium from pulps on sorbents. However, these investigations must be conducted directly at the facilities on real media, since the properties of the indicated systems change sharply in time. The rate of settling of a sorbent in pulp indireedy reflects these properties, and for this reason, once it is determined experimentally, k can then be used for calculations of the hydrodynamic regime in a pulsation column in the pulp-sorbent system.In the initial uranium-containing pulp with density 1.32.10 -3 kg/m 3, the anion exchange AMP, whose density is 1.25" 10-3 kg/m 3, becomes distributed uniformly and is suspended in the volume of the pulp as a result of the high viscosity and density. When this pulp is diluted with water to separate the sand fraction of the pulp and the pulp is washed at the same time, the viscosity and density of the pulp drops sharply and the sorbent starts to settle (see Table 1).According to the data presented in Table 1, the acceptable, for performing counterflow sorption of uranium with AMP from pulp, rate of settling of the sorbent is achieved by diluting the initial pulp by a factor of 2. Not only the hydrodynamic regime in the pulsational column but also the dimensions of the column and the amount of pulp necessary for sorpti...

No abstract