Influence of gravity effect to the recovery rate at uranium in-situ leaching

In-Situ Leaching is a method of extracting minerals by selectively dissolving it with a leaching solution directly in the place of occurrence of the mineral. In practice, during the development of deposits with the In-Situ Leaching method, situations arise when the solution tends to go down below the active thickness of the stratum. This may be due to geological heterogeneity of the rock or gravitational sedimentation of the solution in the rock due to the difference in the densities of the solution and groundwater. As a result of the deposition of the solution along the height, there is a decrease in the recovery of the metal located in the upper part of the geological layers. This article examines the effect of gravity on the flow regime during the filtration of the solution in the rock. The influence of the gravitational effect on the flow of solution in the rock is studied for different ratios of the densities of the solution and groundwater without taking into account the interaction of the solution with the rock. The CUDA technology is used to improve the performance of calculations. The results show that the use of CUDA technology allows to increase the performance of calculations by 40-80 times compared to calculations on a central processing unit (CPU) for different computational grids.

Simulating In-Situ Leaching Process Using Comsol Multiphysics

The paper deals with simulation of in-situ uranium leaching technological process, collecting data for forecasting and leaching process control. It provides numerical simulation of uranium in-situ leaching (ISL) using Comsol Multiphysics software package application. Previous studies evaluated main hydrodynamic characteristics of wells and reservoirs, such as the coefficient of resistance and the saturation recovery; while this paper is concerned with determining the changes in process variables in the wells during operation.

Remediation of Uranium In-Situ Leaching Area at Stráž pod Ralskem, Czech Republic

A large-scale development in exploration and production of uranium ores in the Czech Republic was done in the 2nd half of the 20th century. Many uranium deposits were discovered in the territory of the Czech Republic. One of the most considerable deposits in the Czech Republic is the site Hamr na Jezere – Straz pod Ralskem where both mining methods — the underground mining and the acidic in-situ leaching — were used. The extensive production of uranium led to widespread environmental impacts and contamination of ground waters. Over the period of “chemical” leaching of uranium (ca. 32 years), a total of more than 4 million tons of sulphuric acid and other chemicals have been injected into the ground. Most of the products (approx. 99.5 %) of the acids reactions with the rocks are located in the Cenomanian aquifer. The contamination of Cenomanian aquifer covers the area larger then 27 km2. The influenced volume of groundwater is more than 380 million m3. The total amount of dissolved SO42− is about 3.6 million tons. After 1990 a large-scale environmental program was established and the Czech government decided to liquidate the ISL Mine and start the remediation in 1996. The remediation consists of contaminated groundwater pumping, removing of the contaminants and discharging or reinjection of treated water. Nowadays four main remedial technological installations with sufficient capacity for reaching of the target values of remedial parameters in 2037 are used — the “Station for Acid Solutions Liquidation No. One”, the “Mother liquor reprocessing” station, the “Neutralization and Decontamination Station NDS 6” and the “Neutralization and Decontamination Station NDS 10”. It is expected that the amount of withdrawn contaminants will vary from 80 000 to 120 000 tons per year. Total costs of all remediation activities are expected to be in excess of 2 billion EUR.

The Decreasing Ways of Contaminated Underground Water Volume in Uranium Mining and Milling Region

Ukrainian uranium ore mining and milling facilities are located in the tight populated areas on the valuable agricultural lands of Ukraine. The almost 50th years’ activity of these enterprises has caused the radioactive contamination of the environment. The most dangerous facilities happened to be those ones which contaminate the entrails for a long time, namely: tailings which were discharged with the uranium ore uranium mill and former uranium in-situ leaching sites which are now decommissioned and left without relevant environmental protection measures. This paper considers two uranium facilities, which impact in a similar way on such an environmental entity as underground water: the tailings and in-situ leaching site located in Dnipropetrovsk region.