Kinetic test

T Higuchi, S Dayal, I Pitman. Effects of solute-solvent complexation reactions on dissolution kinetics Testing of a model by using a concentration jump technique. J Pharm Sci 61 695, 1972. 

The microautoclave solvent activity tests measure coal conversion in a small batch reactor under carefully controlled conditions. The tests are described as Kinetic, Equilibrium and SRT. The Kinetic and Equilibrium Tests measure coal conversion to tetrahydrofuran solubles at conditions where conversion should be monotonically related to hydrogen transfer. The Kinetic Test is performed at 399°C for 10 minutes at an 8 to 1 solvent to coal ratio. The combination of high solvent ratio and low time provide a measure of performance at essentially constant solvent composition. The measured conversion is thus related to the rate of hydrogen donation from solvent of roughly a single composition. In contrast, the Equilibrium Test is performed at 399°C for 30 minutes at a 2 to 1 solvent to coal ratio. At these conditions, hydrogen donors can be substantially depleted. Thus performance is related to hydrogen donor... 

Autoclave Results - Solvent Activity Test. The initial microautoclave work was done with tetralin and methylnaphtha-lene, using Indiana V bituminous coal (Table I). Base line data is shown in Figure 4. All three tests, Kinetic, SRT, and Equilibrium, show an increase in coal conversion with an increase in the concentration of tetralin. The Equilibrium Test shows the highest coal conversion of approximately 86 wt% of the MAF coal (based on the solubility in the tetrahydrofuran) at the 50% tetralin concentration. The Kinetic Test shows lower coal conversion. The hydrogen transferred to the coal from the tetralin in the Equilibrium Test at the 50 wt% tetralin feed concentration is approximately 0.5 wt% of the MAF coal. In the Kinetic Test 50 wt% tetralin feed concentration results in a much smaller transfer at the short reaction time of 10 minutes. 

This reaction can be used as a kinetic test to determine which radicals predominate in an alcohol oxidized under given conditions. If hydroxyperoxide radicals predominate, the... 

Adding Value to Kinetic Testing Data I - Interpretation of Tailings Humidity Cell Data from the Perspectives of Aqueous Geochemistry and Mineralogy at the Crowflight Minerals, Bucko Lake Nickel Project... 

KEYWORDS Kinetic Testing, AMD, Tailings, Aqueous Speciation, PHREEQC, Nickel Mining. 

Estimation and prediction as to whether waste rock and tailings will produce acid mine drainage (AMD) are precursory to environmental certification, and therefore are a critical step in mine development. Kinetic tests are carried out using a cell or column that are operated over a period of typically 1 year, whereas static tests are a onetime measurement to determine the acid producing potential (AP) and... 

Kinetic testing of the rougher tails sample was carried out in accordance with standard ASTM, 2001. Leachate samples were collected each week for 76 weeks and analyzed for a range of parameters including conductivity, pH, acidity, total alkalinity, sulfate and a suite of dissolved metals. Dissolved metals and metalloids were determined by ICP-MS, other parameters by titration or selective ion electrode methods. 

The most likely mineral phases to oxidize under the kinetic testing conditions are the sulfides. Acidity generated from their oxidation is likely to react with calcite and to a lesser extent magnesite. Talc minerals are unlikely to react with leachate. Expected reactions are therefore of the forms ... 

Table 1. Mean dissolved concentrations for chalcopyrite and pentlandite periods of kinetic tests... 

Day, S.J., Hope, G., Kuit, W. 1997. Waste rock management planning for the Kudz Ze Kayah project, Yukon Territory 1. Predictive Static and Kinetic Test Work. Proceedings of the 4th International Conference on Acid Rock Drainage. Vancouver, I, 81-98. 

Frostad, S., Klein, B., Lawrence, R.W. 2002. Evaluation of laboratory kinetic test methods for measuring rates of weathering. Mine Water and the Environment, 21, 183-192. 

Lapakko, K.A. White, W.W.III. 2000. Modification of the ASTM 5744-96 kinetic test. Proceedings from the 5th International Conference on Acid Rock Drainage. Littleton, 631-639. 

KEYWORDS Tailings, Acid mine drainage, Static and kinetic tests, quantitative mineralogy,... 

Fig. 2. Graphical representations of the evolution of cumulative concentrations of sulfur, calcium and magnesium collected throughout the kinetic test.

Benzaazoua, M., Bussiere, B., Dagenais, A.M. 2001. Comparison of kinetic tests for sulfide mine tailings. In Tailings and Mine Waste "01" Fort Collins, Colorado, January. Balkema, Rotterdam, 263-272. 

Adding value to Kinetic Testing Data II - Interpretation of waste rock humidity cell data from an exploration perspective at the Adanac Molybdenum Corporation, Ruby Creek Molybdenum Project, BC,... 

This paper outlines a novel approach to maximising the value of kinetic data by combining mineralogy, aqueous geochemistry and kinetic test data to design ground and surface water exploration programs. The approach is tested on environmental data collected by Adanac Molybdenum Corporation at the Ruby Creek Molybdenum project, Atlin, BC, Canada. 

This methodology allowed periods of sulfide oxidation to be identified in all three sets of kinetic test data. 

Detailed interpretation of kinetic test data collected for environmental purposes has allowed criteria for ground and surface water geochemical exploration to be selected. Parameters predicted from kinetic testing to be anomalous in both ground and surface waters were observed to occur reflecting the presence of both molybdenum mineralization and natural acid rock drainage. Kinetic testing is very expensive and careful use of the acquired... 

The pH values measured in the kinetic tests are shown in Figure 1. The pH of all waste rock samples remain stable between 7 and 8 after 200 days until the end of the test, suggesting conditions will remain near-neutral in the field. 

---