Mineral processing analysis in artisanal gold mining, Peru

Peer ReviewedPostprint (published version

Thermographic non-destructive evaluation for natural fiber-reinforced composite laminates

Natural fibers, including mineral and plant fibers, are increasingly used for polymer composite materials due to their low environmental impact. In this paper, thermographic non-destructive inspection techniques were used to evaluate and characterize basalt, jute/hemp and bagasse fibers composite panels. Different defects were analyzed in terms of impact damage, delaminations and resin abnormalities. Of particular interest, homogeneous particleboards of sugarcane bagasse, a new plant fiber material, were studied. Pulsed phase thermography and principal component thermography were used as the post-processing methods. In addition, ultrasonic C-scan and continuous wave terahertz imaging were also carried out on the mineral fiber laminates for comparative purposes. Finally, an analytical comparison of different methods was give

Processing mineral raw materials

Processing of raw materials by the producer countries themselves has frequently been recommended as an appropriate way for developing countries to increase their domestic value added and achieve positive employment effects. As against that, the following article suggests that Third World governments should not take hasty investment decisions in favour of processing raw materials since the effects on the national economy in terms of the cost-benefit ratio could well be more favourable in other branches of industry

Enzymatic browning of potatoes is greatly reduced with organic fertilization compared to mineral fertilization

Enzymatic browning of tubers owing to mechanical injury is assessed to indicate bad quality, mainly for visual reasons. Browning is also a serious problem during processing of potatoes. The effect of farmyard manure and mineral fertilization at three levels (50, 100, 150 kg total N per hectare) on darkening of potato extract was investigated in three years in a field trial. The extinction of the extract was measured at 400 nm for two days at three dates during the storage period from autumn to spring. The extract of organically fertilized tubers hat a lower extinction compared to the mineral treatments. This difference occurred right at the beginning of the test with the fresh extract as well as during the following two days, when darkening continued with all samples, but with different extent. Whereas increasing manure levels reduced browning, higher amounts of mineral fertilizer intensified the dark colour. During storage from October to April the extinction showed no clear tendency. Polynomial regressions were calculated for the extinction values during the two days after production of the extracts. The R2 values decreased during storage from 0.95 - 0.98 in November to 0.80 - 0.91 in February. This may be interpreted as a hint of progressing disintegration

Organic Fertilization In A “Tomato – Pea” Rotation In Southern Italy

The use of alternative to mineral fertilizers is an important issue in organic systems. A four-year field experiment to evaluate the effects of organic fertilizers on yield and quality of processing tomato and proteic pea in rotation, was carried out in Southern Italy. The fertilization treatments aimed to supply 100 kg ha-1 of N for tomato and 60 kg ha-1 of P2O5 for pea and were: 1) an organic biological fertilizer (BIO); 2) an experimental compost obtained by olive residues, sludge and straw mixture (COMP); 3) a control managed with traditional chemical fertilizers (ammonium nitrate and perphosphate, MIN). At harvest, the main productive and qualitative parameters were assessed. Tomato fruit yield did not differ among the fertilization treatments, but unripe fruit yield was higher in the MIN and BIO treatment; MIN showed also smaller fruit than BIO and COMP. The N availability during crop cycle influenced the mean fruit weight and maturity date. No difference among treatments was observed for pea in rotation with tomato and, similarly, on the wheat cropped without fertilization following the two crops. The possibility to use organic fertilizer for processing tomato and proteic pea has been evaluated and the conclusion is that organic fertilization is comparable to mineral one from a productive and qualitative point of view

Lunar resource evaluation and mine site selection

Two scenarios in this evaluation of lunar mineral resources and the selection of possible mining and processing sites are considered. The first scenario assumes that no new surface or near-surface data will be available before site selection (presumably one of the Apollo sites). The second scenario assumes that additional surface geology data will have been obtained by a lunar orbiter mission, an unmanned sample return mission (or missions), and followup manned missions. Regardless of the scenario, once a potentially favorable mine site has been identified, a minimum amount of fundamental data is needed to assess the resources at that site and to evaluate its suitability for mining and downstream processing. Since much of the required data depends on the target mineral(s), information on the resource, its beneficiation, and the refining, smelting, and fabricating processes must be factored into the evaluation. The annual capacity and producing lifetime of the mine and its associated processing plant must be estimated before the resource reserves can be assessed. The available market for the product largely determines the capacity and lifetime of the mine. The Apollo 17 site is described as a possible mining site. The use of new sites is briefly addressed

Mineral Processing by Short Circuits in Protoplanetary Disks

Meteoritic chondrules were formed in the early solar system by brief heating of silicate dust to melting temperatures. Some highly refractory grains (Type B calcium-aluminum-rich inclusions, CAIs) also show signs of transient heating. A similar process may occur in other protoplanetary disks, as evidenced by observations of spectra characteristic of crystalline silicates. One possible environment for this process is the turbulent magnetohydrodynamic flow thought to drive accretion in these disks. Such flows generally form thin current sheets, which are sites of magnetic reconnection, and dissipate the magnetic fields amplified by a disk dynamo. We suggest that it is possible to heat precursor grains for chondrules and other high-temperature minerals in current sheets that have been concentrated by our recently described short-circuit instability. We extend our work on this process by including the effects of radiative cooling, taking into account the temperature dependence of the opacity; and by examining current sheet geometry in three-dimensional, global models of magnetorotational instability. We find that temperatures above 1600 K can be reached for favorable parameters that match the ideal global models. This mechanism could provide an efficient means of tapping the gravitational potential energy of the protoplanetary disk to heat grains strongly enough to form high-temperature minerals. The volume-filling nature of turbulent magnetic reconnection is compatible with constraints from chondrule-matrix complementarity, chondrule-chondrule complementarity, the occurrence of igneous rims, and compound chondrules. The same short-circuit mechanism may perform other high-temperature mineral processing in protoplanetary disks such as the production of crystalline silicates and CAIs.Comment: 6 pages, 3 figures, ApJL published versio

Annual report of research progress

The great importance of minerals to a state's sound economy can be no better illustrated than by the discovery of oil and gas in Alaska in 1957 in the Kenai Peninsula. This event has led to the establishment of local basic and secondary industries which in turn will enrich the coffers of the state. In a parallel manner, the discovery of oil and gas on the North Slope in 1968 will not only produce basic and allied industries but will also be a catalyst assisting the development of other mineral resources to provide a diversification of industry--so important to the long range economic strength of a state. Also, further economic development of mineral resources is, to a large degree, dependent on mineral science research in the same way that research and development were necessary to develop the jet engine and hence, give a break-through in air transportation; thus, without geological and mineral processing research, mines cannot continue to be found and developed. The following pages will provide evidence of a significant contribution toward the shortening of the knowledge gap in mineral search instrumentation, gold size distribution, coal processing, prospector education, resource evaluation, and exploration oriented computer techniques. The demand by the Alaskan public, industry, and governmental agencies for this information has justified the reprinting of several of this year's research reports. This response by industry and the public has given increased impetus to the goal of MIRL: to aid in the expansion of Alaska's mineral economy through a program of applied and basic research--to seek knowledge today for use tomorrow. Earl H. Beistline, Dean, CESM