VNIPIpromtekhnologii, Moscow, Russia:

A. V. Gladyshev, CEO, Gladyshev.A.V@vnipipt.ru

Atomredmetzoloto, Moscow, Russia:
I. N. Solodov, Director of Innovation and Technological Advance Programs

Uranium production by in-situ leaching (ISL) includes traditional appraisal of uranium reserves per operating blocks and ore bodies by means of regular measurement of the production well yield and uranium content of pregnant solutions. The mathematical geotechnology modeling using physicochemical hydrodynamics produces somewhat erroneous results as any geological modeling does. The errors are connected with the impossibility to take into account nonuniformity of properties and composition of geological environment, as well as with the time-lapse monitoring of the production well yield and uranium content of pregnant solution. The geophysical study carried out in mined-out operating blocks has revealed that anomalous gamma background remains round its initial level even after uranium recovery at a level of 80 % (sometimes 90 %) of the planned production level. It is possible to assess the rate of recovery per ore body areas during ISL and to verify a geotechnology model by integrating the gamma logging and the prompt fission neutron logging during monitor well drilling, emergency redrilling or in construction of extra process wells for densening the process well pattern. As a case-study of specific operating ISL blocks in Khiagda uranium ore province, the article illustrates application of the package of methods including the mathematical geotechnology modeling and reconstruction of initial uranium content by the gamma logging data and from direct estimation of remnant uranium by the prompt fission neutron logging. The integrated use of these methods offers a geoproduction engineer a unique opportunity to control and stimulate ISL towards complete uranium recovery and effective subsoil management.

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