Sequencing of ore columns for planning of large underground mines

This is the final version. Available from Wroclaw University of Science and Technology via the DOI in this record. Block caving is an underground mining technique which extracts ore from the base, rather than from the top, of typically massive deposits. Mining infrastructure is developed below the deposit before extraction commences. A network of tunnels provides access to a collection of drawpoints from which ore is mucked and hauled. With large deposits, not all drawpoints are developed simultaneously and the opening of drawpoints is sequenced to facilitate orderly extraction of ore columns above drawpoints. Sequencing fixes the initiation point for the entire block cave, or a part of it, as well as identifying the direction of cave advancement. The sequence of opening drawpoints influences the mine economics and is an integral aspect of planning a block cave mine. This paper discusses the optimisation of sequencing based on the net present value associated with extraction over the life-of-mine. It is shown that the maximum attainable net present value is obtained by a sequence in which ore columns are ranked in descending order of value. If significant variation of grade is present inside columns, an iterative procedure is given which corrects the sequence which yields the maximum net present value. The sequence with maximum net present value may not be practical or attractive from a caving perspective. Systematic design of sequences which permit orderly development of a block cave is discussed. To provide context, the net present value obtained from these feasible sequences is compared with the maximum attainable net present value. It is shown that the best feasible sequences in terms of net present value are preferentially initiated in zones with columns of high-grade ore.Rio Tinto Technical Services Lt

Sequencing of ore columns for planning of large underground mines

This is the final version. Available on open access from Wroclaw University of Science and Technology via the DOI in this recordBlock caving is an underground mining technique which extracts ore from the base, rather than from the top, of typically massive deposits. Mining infrastructure is developed below the deposit before extraction commences. A network of tunnels provides access to a collection of drawpoints from which ore is mucked and hauled. With large deposits, not all drawpoints are developed simultaneously and the opening of drawpoints is sequenced to facilitate orderly extraction of ore columns above drawpoints. Sequencing fixes the initiation point for the entire block cave, or a part of it, as well as identifying the direction of cave advancement. The sequence of opening drawpoints influences the mine economics and is an integral aspect of planning a block cave mine. This paper discusses the optimisation of sequencing based on the net present value associated with extraction over the life-of-mine. It is shown that the maximum attainable net present value is obtained by a sequence in which ore columns are ranked in descending order of value. If significant variation of grade is present inside columns, an iterative procedure is given which corrects the sequence which yields the maximum net present value. The sequence with maximum net present value may not be practical or attractive from a caving perspective. Systematic design of sequences which permit orderly development of a block cave is discussed. To provide context, the net present value obtained from these feasible sequences is compared with the maximum attainable net present value. It is shown that the best feasible sequences in terms of net present value are preferentially initiated in zones with columns of high-grade ore.Rio Tinto Technical Services Lt

Penalised maximum likelihood estimation in multi-state models for interval-censored data

Continuous-time multi-state Markov models can be used to describe transitions over time across health states. Given longitudinal interval-censored data on transitions between states, statistical inference on changing health is possible by specifying models for transition hazards. Parametric time-dependent hazards can be restrictive, and nonparametric hazard specifications using splines are presented as an alternative. The smoothing of the splines is controlled by using penalised maximum likelihood estimation. With multiple time-dependent hazards in a multi-state model, there are multiple penalty parameters and selecting the optimal amount of smoothing is a challenge. A grid search to estimate the penalty parameters is computational intensive especially when combined with methods to deal with interval-censored transition times. A new and efficient method is proposed to estimate multi-state models with splines where the estimation of the penalty parameters is automatic. A simulation study is undertaken to validate the method and to illustrate the effect of interval censoring. The feasibility of the method is illustrated with two applications

Community pharmacist experiences of providing needle and syringe programmes in Ireland

Background: Community pharmacists are increasingly acknowledged as under-utilized, important and accessible health providers in providing harm reduction support to drug users via needle and syringe programmes (NSP), provision of advice, HIV/Hepatitis testing and as referral mechanism to social, medical and treatment services. We report here on qualitative findings as part of the evaluation of the pilot Pharmacy Needle Exchange (PNEX) programme in Ireland. Objectives: The aim was to understand and illustrate pharmacist experiences of providing NSP. Methods: Of the 107 eligible pharmacies, a total of 70 participated in the national evaluation. Telephone interviews (n=17) and one to-one interviews (n=13) using a semi-structured guide were conducted with 30 pharmacists. Analysis of data was conducted using the Empirical Phenomenological Psychological (EPP) five step protocol. Results: Pharmacist experiences illustrated the largely positive nature of providing NSP, and highlighted needs to develop harm reduction training for pharmacists and appropriate strategies to raise awareness, provide exchange packs to meet the specific needs of the diverse populations of people who inject drugs and ensure the development of trusting relationships and opportunities to engage within a confidential service. Conclusions: Further enhancement of NSP coverage and targeted service delivery within national care pathways for drug and alcohol services is warranted

The Reality of Functionally Graded Material Products

Rapid Manufacturing utilizes the application of different materials in parts by stacking a sequence of layers. Based on the requirements of the part, mixtures of materials, so-called Functionally Graded Materials, can be used to compose the product functionality. This process depends completely on the availability of CAD information of the part geometry. Unfortunately, commercially available CAD-systems do not allow the design of graded material structures. TNO developed a computer tool which enables the user to specify Functionally Graded Materials. The system is based on a new approach to define the material composition at any point in the solid.Mechanical Engineerin

The Dynamic Landscape of Novel Psychoactive Substance (NPS) Use in Ireland: Results from an Expert Consultation

In Ireland, legislators encountered a new phenomenon in 2005 onwards with the advent of ‘legal highs’ sold in headshops. Use of ‘legal highs’ containing herbal and synthetic new psychoactive substances (NPS) was not confined to problematic drug users, and included social recreational users. Legislative controls were enacted in 2010, 2011 and 2015. The study aimed to investigate expert perspectives on the NPS situation with regard to changing and emergent trends in use, health and social consequences and service implications. This brief report presents descriptive findings from a national consultation using a structured guide with experts in 2016. Four themes emerged and centred on; ‘Definitions of NPS used within Professional Roles’; ‘Professional Experiences of NPS‘; ‘Types of NPS Users, Sourcing and Consequences of Use’; and ‘Service Response.’ Findings underscored the mental health and addiction related consequences of NPS use, with prevention, clinical and treatment services ill- equipped to deal with the particular characteristics of this form of drug abuse. Enhanced strategies, services and clinical responses are warranted to address the challenges encountered. © 2016 Springer Science+Business Media New Yor

The impacts and service responses to injecting cathinones and novel opioids amongst marginalized drug using populations – a scoping review

Background: A growing body of literature reports on the injection of synthetic cathinones (SC) and novel synthetic opioids (NSO) in marginalized drug-using (MDU) populations. This review seeks to establish what is known about the injection of SCs and NSOs impacts on MDUs. Method: A six-stage iterative scoping literature review was conducted in relation to SCs, NSOs, MDU impacts and service responses. Searches were conducted through Pubmed™ and Google Scholar™. Results: Two Thousand and Ninety-Nine search items were retrieved. After duplicates were removed (n = 880), articles were screened for injecting drug use by MDUs leading to the removal of a further 1102 articles. Three articles were identified through a hand search, yielding a total of 22 articles for appraisal. Conclusions: SC injection has largely dissipated in many regions due to service and policy responses and changes in the drug market. Responses to NSO have been less effective, with extensive use and opioid overdosing due to contamination and adulteration within the illicit drug market. These impacts have stimulated innovative responses such as fentanyl test strips and housing-based consumption sites. The evidence for their effectiveness is not established. In this context, the underlying environmental and structural factors shaping the risk of these populations should be addressed.info:eu-repo/semantics/acceptedVersio