Evaluation of the One-Well Uranium Leaching Test: Restoration

1982 ◽  
Vol 22 (01) ◽  
pp. 141-150 ◽  
Author(s):  
Muhammad I. Kabir ◽  
Larry W. Lake ◽  
Robert S. Schechter
Keyword(s):  
Acid Leaching ◽  
Leach Solution ◽  
Damkohler Number ◽  
Damköhler Number ◽  
Well Spacing ◽  
Number Of Factors ◽  
Well Pattern ◽  
Mineralized Zone ◽  
Selection Of

Abstract In-situ leach mining for uranium is an emerging technology. Currently, the selection of a well pattern designed to recover mineral values is governed primarily by arguments based on hydrological considerations. The effects of well pattern and well spacing on uranium recovery and oxidant utilization are considered in this paper. As expected, formation permeability heterogeneities and anisotropies are found to be important issues requiring careful consideration, however, it also is shown that chemical factors cannot be ignored. In particular, it is shown that the oxidant efficiency and the produced uranium solution concentrations are sensitive to the presence of other minerals competing with uranium for oxidant. If the Damkohler number for competing minerals, which measures the speed of the reaction, exceeds that for uranium, the competing mineral will have to be oxidized completely to recover a large proportion of the uranium. If the Damkohler number is smaller, it may be possible to achieve considerable selectivity for uranium by adjusting the well spacing. It also is shown that the oxidant efficiency is generally highest for well patterns that give streamlines of roughly equal length and that there is a minimum distance between injection and production wells to utilize oxidant most advantageously. Introduction In-situ solution mining is a process whereby uranium is recovered from permeable sandstone bodies by injecting and producing a leach solution through an array of wells penetrating the mineralized zone. It appears to have broad application and in many situations offers both economic and environmental advantages. The processes may be classified generally as acid or alkaline, but the general features of both are the same. The insoluble uranium in the mineralized zone is in the +4 state of oxidation. To be mobilized, the uranium must be oxidized to the +6 state and complexed either with sulfate in the case of acid leaching or carbonate in the case of alkaline leaching to form highly soluble uranyl sulfates or carbonates. The leach solutions, therefore, contain an oxidant (oxygen, hydrogen peroxide, ferric cations, sodium hyperchlorite, etc.) together with a complexing agent (anion). The choice of leach solution depends on a number of factors including selectivity and injectivity. For example, formations containing more than 1 wt% carbonates are not likely to be candidates for acid leaching because of the large acid requirement and because of permeability loss due to precipitation of calcium sulfate. It is the purpose of this paper to consider the technical factors (as opposed to economic) that govern the choice of well pattern to be used for leaching. The discussion is structured so that the conclusions apply to both alkaline and acid lixiviants and to any oxidant, although an occasional reference to a particular oxidant may appear. Considerable use is made of the computer simulator previously reported. The computational details are available in that paper. A number of factors that pertain to the selection of a well pattern are considered. It is shown that the effectiveness of the oxidant - i.e., the uranium recovered per unit of oxidant injected - is related to the well pattern, to the reaction rates, and to the permeability variations, especially if the formation is anisotropic. Furthermore, the spacing between wells is related to reactions with oxidizable minerals that compete for oxidant. These considerations can be quantified to some extent by studying linear systems. Linear Flow Systems SPEJ P. 132^

Well Pattern Optimization Design for CBM Development

2014 ◽  
Vol 881-883 ◽  
pp. 1225-1229
Author(s):  
Gang Zhao ◽  
Shu Heng Tang ◽  
Xiao Fei Jian
Keyword(s):  
Optimization Design ◽  
Economic Research ◽  
Dimensionless Form ◽  
Qinshui Basin ◽  
Well Spacing ◽  
Well Pattern ◽  
Square Well ◽  
Well Pattern Optimization ◽  
Two Parameters ◽  
Selection Of

CBM well pattern optimization is the key issue for CBM development. Usually the selection of well pattern is a problem to coordinate the cumulative productivity and recovery. For finding the optical well spacing, this article will coordinate the two parameters after they are transformed into dimensionless form. And the economic research for the optimal well spacing is adopted as a supplemented proof. Finally the CBM well pattern of the block in North Qinshui basin must be a square well pattern the 300m×300m is regarded as the optimal well spacing.

Preparation and optimization of nano-sized cocrystals using a quality by design approach

CrystEngComm ◽  
2020 ◽  
Vol 22 (13) ◽  
pp. 2304-2314
Author(s):  
Pradip Thakor ◽  
Balvant Yadav ◽  
Sheela Modani ◽  
Nalini R. Shastri
Keyword(s):  
Quality By Design ◽  
Design Approach ◽  
Damkohler Number ◽  
Damköhler Number ◽  
Design Selection ◽  
Quality By Design Approach ◽  
Selection Of

Nano-cocrystals were optimized using the L-18 Hunter design. Selection of solvent and antisolvent was made using the Damkohler number.

Suitability of Natural Geomedia for Radwaste Storage

1982 ◽  
Vol 15 ◽  
Author(s):  
W. S. Fyfe
Keyword(s):  
Rock Properties ◽  
Fracture Flow ◽  
Time Prediction ◽  
Sedimentary Sequences ◽  
Rock Types ◽  
Direct Observations ◽  
Long Time ◽  
Mining Disturbance ◽  
Selection Of

ABSTRACTSelection of the best rock types for radwaste disposal will depend on their having minimal permeability, maximal flow dispersion, minimal chance of forming new wide aperture fractures, maximal ion retention, and minimal thermal and mining disturbance. While no rock is perfect, thinly bedded complex sedimentary sequences may have good properties, either as repository rocks, or as cover to a repository.Long time prediction of such favorable properties of a rock at a given site may be best modelled from studies of in situ rock properties. Fracture flow, dispersion history, and geological stability can be derived from direct observations of rocks themselves, and can provide the parameters needed for convincing demonstration of repository security for appropriate times.

Synthesis of Magnesia Powder from East Java Dolomite through Leaching, Precipitation and Calcination

2015 ◽  
Vol 1112 ◽  
pp. 550-554
Author(s):  
M. Zaki Mubarok ◽  
Christian Adi Kurniawan
Keyword(s):  
Particle Diameter ◽  
Acid Leaching ◽  
Xrd Analysis ◽  
Sem Analysis ◽  
Leach Solution ◽  
Water Removal ◽  
Solution Ph ◽  
Crystal Water ◽  
Lower Temperature ◽  
Co Precipitation

At the present paper, a process of magnesia (MgO) synthesis from East Java dolomite through hydrochloride acid leaching, precipitation and calcination as well as characteristic of the product is discussed. Results of the experimental works show that the dissolution rate of magnesium and calcium from dolomite in hydrochloride acid solution was very rapid. Complete magnesium extraction was obtained by the leaching test with acid concentration of 1.5 molar, particle size distribution of -325#, solid-liquid ratio 1:20 (g/mL), stirring speed 200 rpm at room temperature after only 10 seconds. Precipitation of Mg(OH)2 by the addition of 20% (v/v) CaO slurry into pregnant leach solution resulted in 97.5% Mg precipitation after 1 minute. Solution pH must be maintained at a level of 10-10.5 by adjusting CaO addition in order to minimize calcium co-precipitation and to obtain high purity of Mg(OH)2 precipitate. Calcinations of Mg(OH)2 were performed at temperature range of 550-800°C in which 99% of crystal water removal took place after 5 minute at temperature of 800°C. Lower temperature requires longer time of crystalline water removal from Mg(OH)2. XRF analysis showed MgO purity of 88% with the main impurities of calcium and chloride. XRD analysis detected the presences of calcium as calcite (CaCO3) and portlandite (Ca(OH)2) as impurities in the MgO product. SEM analysis of the MgO powder revealed a nano size of MgO with particle diameter of about 50 nm.

scholarly journals Strategic selection of an optimal sorbent mixture for in-situ remediation of heavy metal contaminated sediments: Framework and case study

2012 ◽  
Vol 105 ◽  
pp. 1-11 ◽  
Author(s):  
Y.W. Chiang ◽  
R.M. Santos ◽  
K. Ghyselbrecht ◽  
V. Cappuyns ◽  
J.A. Martens ◽  
...  
Keyword(s):  
Heavy Metal ◽  
Contaminated Sediments ◽  
In Situ Remediation ◽  
Selection Of

scholarly journals Prilog poznavanju djelovanja Mateja Andrijina Moronzona*

Ars Adriatica ◽  
2016 ◽  
pp. 103
Author(s):  
Barbara Španjol-Pandelo
Keyword(s):  
Comparative Analysis ◽  
Virgin Mary ◽  
Main Role ◽  
Huge Number ◽  
General Acceptance ◽  
Parish Church ◽  
Archival Documents ◽  
First Time ◽  
Selection Of

Matteo Moronzon, a member of the Venetian family of woodcarvers, was mentioned for the first time in 1407 according to the present known archival documents. Probably after being trained in his father's workshop in Venice, he moved to Zadar with his family – his wife Francisca and sons Pietro and Francesco. In 1418 he undertook the commission of furnishing carved choir stalls for the cathedral of St. Anastasia in Zadar. Various archival documents testify that Matteo lived and worked in Zadar for many years. Therefore it can be assumed that he probably founded his own workshop in Zadar where his son Francesco was trained too. Apart from the attempt to reconstruct Matteo's life and career, the aim of this paper is to interpret one important woodcarving work of art preserved in situ: choir stalls in the former cathedral of Rab, today the arch parish church of the Assumption of the Blessed Virgin Mary in Rab. Without doubt Matteo was the master carver in the production of the choir stalls in Zadar. Since he lived in Zadar it was not unusual that he had the main role in carving the stalls. In Zadar the selection of motives is more balanced and there are no significant differences in the modelling of decorative elements. However, the question whether Matteo carved absolutely everything or he had assistants arises. Considering the amount of work that had to be done it must be assumed that he had assistants who participated in work and helped him to shape the stalls. However, in literature Matteo was considered the only and undisputed author of the choir stalls in Zadar, mostly because of the preserved document. The analysis of the choir stalls in Rab by Ivo Petricioli as well as their evident formal and stylistic similarities with the stalls from the cathedral in Zadar have led to the general acceptance of the hypothesis that they were carved at the workshop of Matteo Moronzon. However, a comprehensive comparative analysis that could confirm that hypothesis was still missing. The analysis of the details and the whole led to the overall conclusion that there were a huge number of similarities between the choir stalls in Rab and Zadar. Therefore it was concluded that Matteo was the principal designer of the choir stalls in Rab who also carved the best parts in Rab, while others, less successful parts, were made by his apprentices and assistants who at the time lived on the island of Rab. In this respect, if Matteo was accepted as the author of the choir stalls of the cathedral in Zadar he must also be accepted as the author of the choir stalls from the excathedral in Rab.

scholarly journals Transplantation of the Mediterranean seagrass Posidonia oceanica through naturalistic engineering techniques: value, weakness and further improvements

2015 ◽  
Author(s):  
Stefano Acunto ◽  
Luigi Piazzi ◽  
Francesco L. Cinelli ◽  
Anna Maria De Biasi ◽  
Lorenzo Pacciardi ◽  
...  
Keyword(s):  
Environmental Conditions ◽  
Large Scale ◽  
Focal Point ◽  
Posidonia Oceanica ◽  
Hydrodynamic Conditions ◽  
Coastal System ◽  
Pros And Cons ◽  
The Mediterranean ◽  
Selection Of

Transplantation of seagrasses is considered a useful method to favour the recovery of degraded meadows. Hence, many projects have been carried out worldwide and a manifold of techniques have been applied. However, the choice of transplantation procedures remains a main problem to be assessed. In order to optimize efforts and to minimize risks of plants loss, the applied methodologies should take into account typology of hosting substratum, hydrodynamic conditions, depth and seagrass species. Due to their fundamental ecological role in the Mediterranean coastal system, many restoration projects aiming to preserve Posidonia oceanica meadows took place in the last decades. Several transplantation techniques have produced different results. In fact the same transplanting methodology may originate diverse results under different environmental conditions. Recently, naturalistic engineering techniques developed on land, have been used for transplantations of P. oceanica. Pilot projects concerning small surfaces were carried out between 2006 and 2010. More recently, a large-scale program (0.1 km2) was realized in 2012 at Civitavecchia (Roma, Thyrrenian Sea). The applied technique consists basically of mattresses filled with sand coupled with a net covering able to hold steady in situ the plant rhizomes. These structures have been variously modified in time to be adapted to the different type of substratum and various hydrodynamic conditions of the transplanting sites. Following the results of these transplantation experiences, we analyzed pros and cons of the techniques in order to improve the methodology. Firstly, these techniques may be considered suitable to large-scale projects allowing to minimize transplantation times. Secondly, the rhizomes may be successfully fixed to the structures; the majority of the transplanted shoots was not damaged showing a very good vegetative vitality with the production of new rhizomes, leaves and roots few months after transplanting. Finally, this procedure is flexible, as the basic technique can be modified and tailored to the various environmental conditions of the different receiving site. However, the results obtained in different areas are highly heterogeneous suggesting that a careful selection of the hosting site is a focal point. To this aim, a pilot study before the beginning of large-scale project seems mandatory, providing a fundamental support to guarantee successful results.

scholarly journals MULTI-WAVE ULTRASONIC CONTROL OF CONCRETE

2017 ◽  
Vol 16 (4) ◽  
pp. 289-297
Author(s):  
D. Yu. Snezgkov ◽  
S. N. Leonovich
Keyword(s):  
Rayleigh Wave ◽  
Pulse Propagation ◽  
Ultrasonic Method ◽  
Physical And Mechanical Properties ◽  
Pulse Velocity ◽  
Energy Localization ◽  
Near Surface ◽  
In Situ Conditions ◽  
Selection Of

The existing non-destructive testing system of structure concrete is actually orientated on the usage of longitudinal acoustical waves. This is due to simplicity of technical realization for measuring velocity (time) of acoustical pulse propagation in bulk concrete. But a reverse side of simple measuring procedure is a loss of additional information on concrete which is contained in the accepted acoustical signal. Therefore usage of an ultrasonic concrete testing method is limited by assessment of its strength. Joint usage of several wave types, so-called multi-wave testing, allows to refine metrology parameters of the ultrasonic method and to gain more information while determining physical and mechanical properties of concrete in laboratory and in situ conditions. The paper considers testing of elongated concrete elements and structures by an ultrasonic pulsing method on the basis of longitudinal subsurface and Rayleigh waves. It has been proposed to use methodology for time selection of wave components according to amplitude parameter and it has been applied for standard acoustical transformers with considerable reverberation time and not possessing spatial selectivity Basic principle of the proposed methodology is visual (according to oscillogram of the received signal) determination of characteristic time moments which are used for calculation of differential value of a propagation velocity in the Rayleigh wave impulse. The paper presents results pertaining to simulation of acoustical pulse propagation on the basis of 0.15 m and data of concrete ultrasonic in situ testing on measuring bases from 0.25 to 1.75 m. Advantage of large baseline for sonic test is a possibility for execution of a hundred percent inspection for surface of large-sized elements and structures, and so there is no need to make a selective inspection in some control areas as it is stipulated by provided by existing regulations. Responsivity of the Rayleigh wave parameters to near surface concrete defects permits quickly and efficiently to detect crack areas in a reinforced structure. Energy localization of a surface wave in a layer having width λ/2–λ provides a possibility to ignore reinforcement availability under appropriate selection of oscillation frequency. In addition to this, large measuring baseline makes it possible to lower effect of concrete structural inhomogeneity on statistical stability for pulse velocity assessment that ultimately reveals a possibility to register an appearance of concrete acoustical elasticity effect under in situ conditions.

Sign in / Sign up

Export Citation Format

Share Document