Groundwater recovery simulation for determination of post-mining lake formation at the Sangan iron mine, Mashhad, Iran

A two-dimensional axisymetric finite element software SEEP/W was used to simulate the groundwater recovery process in wells entirely confined in an aquifer at Sangan iron mine in Iran. The simulation model predicted very well with the results obtained from both analytical method and field data for well recovery process. It was inferred from the results that the rate of groundwater recovery process is highest immediately after mine closure with no dewatering program. The paper presents a methodology for predicting how the natural groundwater regime can be established to its equilibrium conditions after mining operation has ceased

Investigation of Alkali Threshold Limits and Blended Aggregate in ASR Risk-Assessed Concretes

Concrete structures are designed for a specific design life to tolerate deterioration caused from various aggressive environmental loads such as carbon dioxide, chloride and aggressive soil conditions. The approach to prevent deterioration in concrete due to alkali-silica reaction (ASR) is by the avoidance of any such dissolution reaction taking place in concrete. ASR can in part be prevented by limiting the alkali content and restricting the use of potentially reactive aggregates. In this paper, the alkali threshold of several aggregates originating from New Zealand were determined using a modified version of RILEM AAR-3.2 and AAR-7.1. The AAR-2 accelerated mortar bar test (AMBT at 80°C) and AAR-3.2 concrete prism test (CPT at 38°C) were replaced with Australian Standard AS 1141.60.1 and 60.2 test methods, respectively, to evaluate expansion. Additional accelerated CPT in accordance with AAR-4.1 (ACPT at 60°C) was also conducted to examine the adequacy of shortening the test period. Petrographic examination taken before and after expansion testing was also carried out to qualify the presence of reactive silica and ASR gel contributing to expansion. The findings of this study suggest the potential for specifying the alkali threshold in concrete based on the reactivity classification of aggregates allowing a relaxation of the CCANZ Technical Report TR 3 alkali limit of 2.5 kg/m3 that is currently in place in New Zealand. This approach allows greater flexibility in the use of potentially reactive aggregates as sustainable concreting making materials

Mitigating Alkali Silica reactions in the absence of SCMs: A review of empirical studies

© 2019 by the fib. All rights reserved. The mechanism and severity of alkali-silica reaction (ASR) is subjective to the conditions of the availability of moisture and sufficient alkali content, and the presence of reactive aggregates. Since the 1940s, key focus has been placed on the reduction of alkali content by way of addition of supplementary cementitious materials (SCMs). However, the cost of SCMs and the realization that the availability of these materials could become limited in the untold future has influenced some researchers to investigate the development of protocols for the use of aggregates minimizing the likelihood of potential severe ASR. This paper presents a summary and review of the various strategies that have been adopted in recent years for the mitigation of ASR without utilising the addition of SCMs

Deployment of self-contained self rescuers in coal mines

Field trials at three New South Wales and one Queensland coal mines were carried out to gather data on oxygen .\u27run out times of Self-Contained Self Rescuers (SCSRs), time taken to escape from the mine, distances travelled and the average heart rate of subjects wearing SCSRs. The study has led to a method of predicting the duration of oxygen supply from a SCSR as a function of the wearer\u27s body weight. physical fitness and the prevailing environmental conditions. Escapeway design, planning for emergencies, familiarity with SCSRs and experiential escape training are critical to control panic and maxirnise the likelihood of survival of a person attempting to escape in an emergency involving fIre or explosion

An evaluation of airborne laser scan data for coalmine subsidence mapping

The accurate mapping of coalmine subsidence is necessary for the continued management of potential subsidence impacts. The use of airborne laser scan (ALS) data for subsidence mapping provides an alternative method to traditional ground-based approaches that affords increased accessibility and complete spatial coverage. This paper evaluates the suitability and potential of ALS data for subsidence mapping, primarily through the examination of two pre-mining surveys in a rugged, densely vegetated study site. Data quality, in terms of mean point spacing and coverage, is evaluated, along with the impact of interpolation methods, resolution, and terrain. It was assumed that minimal surface height changes occurred between the two pre-mining surfaces. Therefore any height changes between digital elevation models of the two ALS surveys were interpreted as errors associated with the use of ALS data for subsidence mapping. A mean absolute error of 0.23 m was observed, though this error may be exaggerated by the presence of a systematic 0.15 m offset between the two surveys. Very large (several metres) errors occur in areas of steep or dynamic terrain, such as along cliff lines and watercourses. Despite these errors, preliminary subsidence mapping, performed using a third, post-mining dataset, clearly demonstrates the potential benefits of ALS data for subsidence mapping, as well as some potential limitations and the need for further careful assessment and validation concerning data errors

Evaluation of sweetpotato accessions for end-user preferred traits improvement

This study assessed the genetic diversity and differentiation in sweetpotato accessions in Ghana to guide selection for genetic improvement on beta-carotene, dry matter and sugar contents to promote increased utilization. One hundred and fifteen sweetpotato accessions from four different sources, which were the International Potato Centre (CIP) collection, local collection from farmers’ field, local improved varieties, and local and exotic collections from the National Agricultural Research Programmes were studied using 40 agro-morphological and physico-chemical traits, and 25 SSR markers. Variability was obtained for 13 agro-morphological traits and all the physico-chemical traits. Significant genetic diversity indicates existence of a high degree of agro-morphological and physicochemical variation. Within Group variation (97%) accounted for most of the diversity indicating a broad genetic base. The divergence indicates that breeders can form different populations with significant levels of genetic variation to exploit heterosis and improvement of populations. A strong negative relationship was found for sugar content and dry matter content and indicates a possible development of non-sweet high dry matter sweetpotato varieties. However, developing non-sweet, high dry matter and high beta-carotene sweetpotato varieties could be challenging due to the strong negative association between dry matter content and beta-carotene content, and the positive association existing between beta-carotene and sugar content. This study has in addition confirmed the breeding potential of sweetpotato accessions in Ghana and the probability of providing useful genetic variation for the development of farmer preferred cultivar

Constraints and breeding priorities for increased sweetpotato utilization in Ghana

Sweetpotato is used in various food preparations in place of rice, cassava, yam and plantain in Ghana. In spite of this it does not have the same importance in Ghanaian diet as other root and tuber crops. Consumer taste, preference and acceptance are critical in determining the suitability of sweetpotato cultivars to any locality. A study was carried out in some selected communities of Ghana where sweetpotato is popular which span all five ecozones of Ghana in February, 2012. The main objective was to investigate why sweetpotato has low utilization compared with other root and tuber crops and to increase its utilization through breeding. The study employed Focus Group Discussion (FGD) followed by administration of Semi-structured Questionnaire (SSQ). Data collected were analysed using Genstat and Statistical Package for Social Sciences. Seventy-nine people consisting of 63% males and 37% females, and 178 people consisting of 52% female and 48% males were involved in the FGD and SSQ, respectively. Majority (94%) of farmers’ ranked sweetpotato from 1 to 5 among 24 cultivated crops. Only about 28% of consumers ate sweetpotato at least six days per week. The survey revealed that consumers in Ghana desired non-sweet, high dry matter sweetpotato cultivars. Therefore, there is need for Research and Development to adjust sweetpotato breeding objectives and selection procedures to develop high dry matter non-sweet sweetpotato varieties in Ghan

Yield, biochemical properties and cooking quality traits of sweet potatoes (Ipomoea batatas) as affected by Nitrogen and Potassium Fertilizer rates

This study evaluated the effects of mineral fertilizer rates on biochemical properties, cooking quality traits and root yield of sweetpotatoes. The experimental design was 4 x 4 factorial in randomized complete block with three replications. The treatment factors were four varieties of sweetpotato (Ligri, Bohye, Dadanyuie and Apomuden) and four fertilizer amendments (T1: 30-30-30 kg /ha NPK, T2: 30-30-60 kg NPK+50 kg Muriate of Potash, T3: 30-30-90 kg/ha NPK+ 100 kg Muriate of Potash and T4: Control (No fertilizer). Results showed that the fertilizer rates did not influence root yield but variety had significant difference (P<0.05). Apomuden recorded the highest average root yield of 14.5 t/ha which was significantly higher than Ligri 5.1 t/ha. Ligri recorded the highest dry matter and sugar contents of 34.63% and 67.98% respectively while Apomuden recorded the lowest dry matter content and starch content of 23.75% and 50.00% respectively. However, it recorded appreciable amount of beta-carotene and sugar contents of 32.38 mg/100g and 28.04% respectively. There were significant variety × location interactions effect (P < 0.05) on average root yield and biomass yield. The significant varietal response observed in this study implies that choice of variety is an important factor to consider in sweetpotato production