Tar sand pretreatment with diluent

Journal ArticleImportant aspects of kerosene penetration into tar sand have been investigated. The natural tar sand porosity was measured and used to analyze the performance of the hot water process. Subsequently, pretreatment experiments, using 20-kg tar sand samples (Asphalt Ridge and Whiterocks, Utah) and kerosene as a diluent were carried out at the expected summer temperature (26°C) and the expected winter temperature (-14°C). The natural tar sand porosity accessible by diluent has a crucial impact on the reduction of bitumen viscosity and influences the penetration time required for successful bitumen separation from tar sand by hot water processing. Thus, the tar sand porosity is a critical variable that determines appropriate operating conditions. Experimental results indicate that diluent penetration into the Asphalt Ridge tar sand (high porosity) is almost complete after 30 min, where as for the Whiterocks tar sand (low porosity) the penetration process is much slower, being still incomplete after 15 hours regardless of the ambient temperature

Air-sparged hydrocyclone (ASH) technology for cyanide recovery

Journal ArticleAn air-sparged hydrocyclone (ASH) mobile system was evaluated for continuous stripping and recovery of cyanide (the AVR process) from process water at a gold plant site. The ASH unit performed exceptionally well as an absorber. HCN was absorbed from the gas phase in a single pass with an efficiency exceeding 99%. HCN concentration in the discharged gas phase was lower than lOppm, which provided for a safe working environment. The stripping efficiency, controlled by the Henry's Law constant, exceeded 40% in one pass

Methodological issues in cross-cultural research

Regardless of whether the research goal is to establish cultural universals or to identify and explain cross-cultural differences, researchers need measures that are comparable across different cultures when conducting cross-cultural studies. In this chapter, we describe two major strategies for enhancing cross-cultural comparability. First, we discuss a priori methods to ensure the comparability of data in cross-cultural surveys. In particular, we review findings on cross-cultural differences based on the psychology of survey response and provide suggestions on how to deal with these cultural differences in the survey design stage. Second, we discuss post hoc methods to ascertain data comparability and enable comparisons in the presence of threats to equivalence

Computational Models of Classical Conditioning guest editors’ introduction

In the present special issue, the performance of current computational models of classical conditioning was evaluated under three requirements: (1) Models were to be tested against a list of previously agreed-upon phenomena; (2) the parameters were fixed across simulations; and (3) the simulations used to test the models had to be made available. These requirements resulted in three major products: (a) a list of fundamental classical-conditioning results for which there is a consensus about their reliability; (b) the necessary information to evaluate each of the models on the basis of its ordinal successes in accounting for the experimental data; and (c) a repository of computational models ready to generate simulations. We believe that the contents of this issue represent the 2012 state of the art in computational modeling of classical conditioning and provide a way to find promising avenues for future model development

Impact of water recycle on water-based processing of Whiterocks tar sands

Water recycle is an essential part of the hot water process for bitumen recovery from Utah tar sands. The current investigation was primarily designed to evaluate the direct recycle of process water after separation of coarse sand particles. Representative Whiterocks tar sand samples were used in all experiments. Tar sand tailings, after bitumen air flotation, were left 10 min. for sedimentation, and the supernatant containing 4 to 5 wt% suspended matter was used in hot water batch experiments with 8 kg tar sand feed. For the processing conditions used (temperature 50-60°C, pH at digestion <9.5, recycled water) it was found that complete water recycle had no deleterious effect on the separation efficiency after six cycles