Current state of fine mineral tailings treatment: A critical review on theory and practice

The mining industry produces fluid fine mineral tailings on the order of millions of tonnes each year, with billions of tonnes already stored globally. This trend is expected to escalate as demand for mineral products continues to grow with increasingly lower grade ores being more commonly exploited by hydrometallurgy. Ubiquitous presence and enrichment of fine solids such as silt and clays in fluid fine mineral tailings prevent efficient solid-liquid separation and timely re-use of valuable process water. Long-term storage of such fluid waste materials not only incurs a huge operating cost, but also creates substantial environmental liabilities of tailings ponds for mining operators. This review broadly examines current theoretical understandings and prevalent industrial practices on treating fine mineral tailings for greater water recovery and reduced environmental footprint of mining operations

SAP Based Rapid Dewatering of Oil Sands Mature Fine Tailings

Mature fine tailings (MFT), as a mixture of residual bitumen, sand, silt, fine clay particles and water, are a byproduct of oil sands extraction. The large volume, and poor consolidation and water release ability of MFT have been causing significant economic and environmental concerns. Therefore, several studies have been implemented on finding innovative dewatering/disposal techniques. As a result, different methods have been introduced and tested at a laboratory or a field scale, yet very few of these are commercially used in the oil sands industries. Despite the extensive research, an optimal solution has not been found due to the lack of technical or economic feasibility. In the present study, a novel approach that consists of the rapid dewatering of MFT by using a super absorbent polymer (SAP) to produce dense MFT is proposed. A comprehensive laboratory investigation on the geotechnical characteristics and behavior before and after treatment of MFT is conducted. The effects of SAP based dewatering and freeze/thaw cycles on the undrained shear strength of dewatered MFT by using a vane shear apparatus are studied. Furthermore, the ability of recycled SAP to dewater and densify MFT is assessed. Finally, this study provides the results of consolidation and hydraulic conductivity testing to evaluate the void ratio versus effective stress and hydraulic conductivity of MFT. The effects on the behavior and characteristics of MFT after amendment with usage of recycled SAP are also investigated. The results indicate that SAP has the ability to significantly dewater, densify and increase the undrained shear strength of MFT. Furthermore, when subjected to freeze/thaw cycles, the MFT dewatered with SAP shows an additional increase in strength and solid content. It is also found to be possible to regenerate the polymer (still within sachets) through light thermal drying, and the regenerated SAP can still significantly dewater and thus increase the shear strength and solid content of the MFT. In addition, the obtained high solid content affects and improves the compressibility of the material, thus resulting in low initial void ratios. On the other hand, low hydraulic permeability that is derived from low initial void ratios and consolidation is improved by the freeze/thaw process due to the interconnected voids created during the freezing process

Analysis of Bearing Failure

Detta arbete utförs på uppdrag av Skara Sommarland. Arbetet belyser den korta lagerlivslängden hos en maskin som finns på karusellen Spinner. Arbetet belyser även identifieringen av orsaken till lagerhaveriet samt möjliga parametrar som påverkar orsaken. Oförutsägbara haverier medför höga kostnader dels på grund av att underhåll utförs alltför ofta och dels att en oftare uppehållstid leder till färre kunder, vilket resulterar i ekonomiska förluster för företaget. En mikroskopiundersökning på några havererade lager utfördes, för att kunna identifiera, kategorisera samt jämföra mikroskopibilderna med SKF:s referensbilder för liknade typ och orsak av skada. Resultatet av genomförda analyser visar att olämpliga belastningarna inte är den huvudsakliga parametern till haveriorsaken. Resultatet av mikroskopanalysen visar tydliga skador i form av repor, spår och fördjupningar som uppstår på grund av inträngda partiklar i lagrets innerdelar. För att undvika eller åtminstone minimera den korta lagerlivslängden bör hänsyn till nämnda förbättringar i arbetet beaktas. Ett exempel på förbättringsförslag är att använda någon form av skydd för att minska eller förhindra insläpp av fukt och vatten. Två skyddskoncept har utvecklats som förslag på hur ett sådant skydd kan se ut. Koncepten har utvecklats med avseende på först och främst insläpp av vatten. För att få ett mer noggrant och säkert resultat på att det är just föroreningar som orsakar haveriet bör flera antal lager analyseras under ett mikroskop i framtiden.The short lifespan of a bearing is analyzed in a carousel wheel at Skara Sommarland. The aim of this report is to find the cause of failure for the bearing. The machine that is to be analyzed is mounted on the ground between the rails. Unpredictable breakdowns for the machine causes high expenses, as maintenance has to be carried out and the carousel has to be shut down, which makes it unable to generate revenue from customers. A number of bearings was analyzed using a microscope. The purpose of this analysis was to identify, categorize and compare the microscope pictures with SKF’s reference pictures. Results from the analysis show that the unsuitable loads have very little effect on bearing failure. Results from the microscope analysis shows clear images of damage in the bearing. Traces of scratches and indentations on the inside indicates that dust and particles have contaminated the bearing. The pictures also show rust on the inside of the bearing. To avoid or minimize the problem of short bearing life, some improvements are suggested. One suggestion is to make some sort of cover to lower or prevent moisture and water from entering the bearing. Two concepts for the cover were developed for suggestions on how these bearing covers might look like. The concepts were mainly developed to keep water out of the bearing. To ensure that contaminations are the biggest cause of bearing failure, more microscope analyses of the bearings should be performed in the future

Analysis of Bearing Failure

Detta arbete utförs på uppdrag av Skara Sommarland. Arbetet belyser den korta lagerlivslängden hos en maskin som finns på karusellen Spinner. Arbetet belyser även identifieringen av orsaken till lagerhaveriet samt möjliga parametrar som påverkar orsaken. Oförutsägbara haverier medför höga kostnader dels på grund av att underhåll utförs alltför ofta och dels att en oftare uppehållstid leder till färre kunder, vilket resulterar i ekonomiska förluster för företaget. En mikroskopiundersökning på några havererade lager utfördes, för att kunna identifiera, kategorisera samt jämföra mikroskopibilderna med SKF:s referensbilder för liknade typ och orsak av skada. Resultatet av genomförda analyser visar att olämpliga belastningarna inte är den huvudsakliga parametern till haveriorsaken. Resultatet av mikroskopanalysen visar tydliga skador i form av repor, spår och fördjupningar som uppstår på grund av inträngda partiklar i lagrets innerdelar. För att undvika eller åtminstone minimera den korta lagerlivslängden bör hänsyn till nämnda förbättringar i arbetet beaktas. Ett exempel på förbättringsförslag är att använda någon form av skydd för att minska eller förhindra insläpp av fukt och vatten. Två skyddskoncept har utvecklats som förslag på hur ett sådant skydd kan se ut. Koncepten har utvecklats med avseende på först och främst insläpp av vatten. För att få ett mer noggrant och säkert resultat på att det är just föroreningar som orsakar haveriet bör flera antal lager analyseras under ett mikroskop i framtiden.The short lifespan of a bearing is analyzed in a carousel wheel at Skara Sommarland. The aim of this report is to find the cause of failure for the bearing. The machine that is to be analyzed is mounted on the ground between the rails. Unpredictable breakdowns for the machine causes high expenses, as maintenance has to be carried out and the carousel has to be shut down, which makes it unable to generate revenue from customers. A number of bearings was analyzed using a microscope. The purpose of this analysis was to identify, categorize and compare the microscope pictures with SKF’s reference pictures. Results from the analysis show that the unsuitable loads have very little effect on bearing failure. Results from the microscope analysis shows clear images of damage in the bearing. Traces of scratches and indentations on the inside indicates that dust and particles have contaminated the bearing. The pictures also show rust on the inside of the bearing. To avoid or minimize the problem of short bearing life, some improvements are suggested. One suggestion is to make some sort of cover to lower or prevent moisture and water from entering the bearing. Two concepts for the cover were developed for suggestions on how these bearing covers might look like. The concepts were mainly developed to keep water out of the bearing. To ensure that contaminations are the biggest cause of bearing failure, more microscope analyses of the bearings should be performed in the future

Cognitive load theory and educational multimedia

Applying and violating Mayer principles on educational multimedia, and see the effect on EEG, eye data and behavioral data