title: Mining in the Te Aroha mining district during the depression years

authors: Hart, Philip

abstract: Because optimists believed there was payable gold still to be discovered in New Zealand, prospecting was seen as one way of soaking up the unemployed, and a subsidized scheme was established to assist those willing to try their luck. In the Te Aroha district, residents, despite their lack of geological knowledge, and supported by the local newspaper, held great hopes for a mining revival. In contrast, officials and the experts they consulted insisted that these hopes were in vain. After local businessmen and would-be prospectors exerted political pressure on the Minister of Mines, in whose electorate Te Aroha was situated, permission was granted to subsidize parties of amateur prospectors.
Despite none of these parties finding anything worthwhile, the amateurs continued to claim to know more about the prospects than the experts. Some of the parties did little work, and as it was clear to officials that the subsidies were being wasted, these ceased, despite continued claims about potential discoveries. Some parties continued work, sometimes with private backing, prompting concerns about speculators trying to obtain ground. When a Labour Government came to power, it was no more willing than its predecessor to waste public money on fruitless prospecting. It was clear from the assays taken for both prospectors and experts that the value of the ore left by earlier miners was far too poor to permit a revival in mining, and on that note mining ceased at Waiorongomai

text: Mining in the Te Aroha mining district during the depression years Because optimists believed there was payable gold still to be discovered in New Zealand, prospecting was seen as one way of soaking up the unemployed, and a subsidized scheme was established to assist those willing to try their luck. In the Te Aroha district, residents, despite their lack of geological knowledge, and supported by the local newspaper, held great hopes for a mining revival. In contrast, officials and the experts they consulted insisted that these hopes were in vain. After local businessmen and would-be prospectors exerted political pressure on the Minister of Mines, in whose electorate Te Aroha was situated, permission was granted to subsidize parties of amateur prospectors.
Despite none of these parties finding anything worthwhile, the amateurs continued to claim to know more about the prospects than the experts. Some of the parties did little work, and as it was clear to officials that the subsidies were being wasted, these ceased, despite continued claims about potential discoveries. Some parties continued work, sometimes with private backing, prompting concerns about speculators trying to obtain ground. When a Labour Government came to power, it was no more willing than its predecessor to waste public money on fruitless prospecting. It was clear from the assays taken for both prospectors and experts that the value of the ore left by earlier miners was far too poor to permit a revival in mining, and on that note mining ceased at Waiorongomai

year: 2016

title: Tribological properties of thermally sprayed TiAl-Al₂O₃ composite coating

authors: Salman, Asma Siddiq

subjects: engineering

abstract: The use of thermal spray coatings provides protection to the surfaces operating in severe environments. The main goal of the current work is to investigate the possibility of using a high velocity oxy fuel (HVOF) thermally sprayed wear resistant TiAl/Al2O3 coating on tool steel (H13) which is used for making dies for aluminium high pressure die casting. A feedstock of TiAl/Al2O3 composite powder was produced from a mixture of Al and TiO2 powders by high energy mechanical milling, followed by a thermal reaction process. The feedstock was then thermally sprayed using a high velocity oxy-fuel (HVOF) technique onto H13 steel substrates to produce a composite coating. The present study describes and compares the tribological properties such as friction and sliding wear rate of the coating both at room and high temperature (700°C). The results showed that the composite coating has lower wear rate at high temperature (700°C) than the uncoated H13 sample. At Room temperature without using lubricant there is no much significant difference between the wear rate of the coated and uncoated samples. The experimental results showed that the composite coating has great potential for high temperature application due to its lower wear rate at high temperature in comparison with the uncoated sample at the same temperature. The composite coating was characterized using scanning electron microscopy (SEM), optical microscopy and X-ray diffractometry (XRD). This paper reports the experimental observations and discusses the wear resistance performance of the coatings at room and high temperatures.

text: Tribological properties of thermally sprayed TiAl-Al₂O₃ composite coating The use of thermal spray coatings provides protection to the surfaces operating in severe environments. The main goal of the current work is to investigate the possibility of using a high velocity oxy fuel (HVOF) thermally sprayed wear resistant TiAl/Al2O3 coating on tool steel (H13) which is used for making dies for aluminium high pressure die casting. A feedstock of TiAl/Al2O3 composite powder was produced from a mixture of Al and TiO2 powders by high energy mechanical milling, followed by a thermal reaction process. The feedstock was then thermally sprayed using a high velocity oxy-fuel (HVOF) technique onto H13 steel substrates to produce a composite coating. The present study describes and compares the tribological properties such as friction and sliding wear rate of the coating both at room and high temperature (700°C). The results showed that the composite coating has lower wear rate at high temperature (700°C) than the uncoated H13 sample. At Room temperature without using lubricant there is no much significant difference between the wear rate of the coated and uncoated samples. The experimental results showed that the composite coating has great potential for high temperature application due to its lower wear rate at high temperature in comparison with the uncoated sample at the same temperature. The composite coating was characterized using scanning electron microscopy (SEM), optical microscopy and X-ray diffractometry (XRD). This paper reports the experimental observations and discusses the wear resistance performance of the coatings at room and high temperatures.

year: 2009

title: Catchment and lake water quality modelling to assess management options for Lake Tutira

authors: McBride, Chris G.

abstract: Lake Tutira is an important ecological, historical and cultural asset to the Hawke’s Bay. It is a highly utilised trout fishery, a popular recreational destination, and is particularly significant to Ngāti Kahungunu, for its historical eel fishery and rongoa (medicinal) harakeke (flax) beds. The lake and its catchment have been substantially altered from their natural condition, including conversion of forested catchment to pasture, invasion by aquatic macrophytes such as Hydrilla sp., the introduction of grass carp (Ctenopharyngaodon idella) for weed management, and diversion of the largest stream inflow, Papakiri Stream (Sandy Creek), away from the lake and directly to the outflow (Mahiaruhe Stream) in the early 1980s. Lake Tutira’s history of poor water quality dates back decades, with Trophic Level Index (TLI; a metric of overall water quality) values from the 1960s similar to recent years, and blooms of cyanobacteria (blue-green algae) recorded as early as the 1970s. Nevertheless, the years since 2010 have been characterised by very poor water quality and particularly severe blooms, sometimes resulting in near-complete loss of oxygen from surface waters and associated fish kill events. This has attracted media attention and provided impetus from community and stakeholders to assess available management options for restoring more natural conditions and improving water quality in the lake. 
This report examines the drivers of poor water quality and algal blooms the lake, and assesses various management options that have either been specifically proposed for Tutira, or have proven effective for other lakes in New Zealand and globally. Here we report on monitoring undertaken by Hawke’s Bay Regional Council in the catchment (surface inflows) and lake. We also apply state-of-the-art computer models for simulating physical, chemical, and biological processes in the catchment and lake. These simulations are then used to evaluate a range of management ‘scenarios’ to provide guidance on the likely effects of management options tested with the model.

text: Catchment and lake water quality modelling to assess management options for Lake Tutira Lake Tutira is an important ecological, historical and cultural asset to the Hawke’s Bay. It is a highly utilised trout fishery, a popular recreational destination, and is particularly significant to Ngāti Kahungunu, for its historical eel fishery and rongoa (medicinal) harakeke (flax) beds. The lake and its catchment have been substantially altered from their natural condition, including conversion of forested catchment to pasture, invasion by aquatic macrophytes such as Hydrilla sp., the introduction of grass carp (Ctenopharyngaodon idella) for weed management, and diversion of the largest stream inflow, Papakiri Stream (Sandy Creek), away from the lake and directly to the outflow (Mahiaruhe Stream) in the early 1980s. Lake Tutira’s history of poor water quality dates back decades, with Trophic Level Index (TLI; a metric of overall water quality) values from the 1960s similar to recent years, and blooms of cyanobacteria (blue-green algae) recorded as early as the 1970s. Nevertheless, the years since 2010 have been characterised by very poor water quality and particularly severe blooms, sometimes resulting in near-complete loss of oxygen from surface waters and associated fish kill events. This has attracted media attention and provided impetus from community and stakeholders to assess available management options for restoring more natural conditions and improving water quality in the lake. 
This report examines the drivers of poor water quality and algal blooms the lake, and assesses various management options that have either been specifically proposed for Tutira, or have proven effective for other lakes in New Zealand and globally. Here we report on monitoring undertaken by Hawke’s Bay Regional Council in the catchment (surface inflows) and lake. We also apply state-of-the-art computer models for simulating physical, chemical, and biological processes in the catchment and lake. These simulations are then used to evaluate a range of management ‘scenarios’ to provide guidance on the likely effects of management options tested with the model.

year: 2017