The purpose of this paper is to analyse the silver hoards from 10th century Greater Poland in the context of the Piast “state” formation and try to explain the expansion of Piast rulership and power in relation to the long-distance trade.
The paper aims to present directions of transformation of riverside areas in Wrocław implemented in 2012-2018 as well as planned investments within Przedmieście Oławskie revitalization program. Przedmieście Oławskie, a quarter housing estate from the turn of the 19th and 20th centuries is another area being regenerated in Wrocław after Nadodrze. The article outlines projects defined in the Local Revitalization Program for the years 2016-2018, responding to the identified deficits in spatial, social, environmental and economic spheres. The program proposes various projects that will create conditions for further actions. The challenges posed before the revitalization process mean the necessity of undertaking various projects and flexible planning for many years ahead. One of the key actions is a redevelopment of degraded Oława riverfront, which will be an activity and recreation space not only for residents of densely built-up and devoid of green areas Przedmieście Oławskie but also residents of Wroclaw. Modernization of the more than a kilometer section of the wharf can be an impulse for the development of the whole river corridor, that will have high natural, landscape and recreational values. The article discusses the planning process, objectives, principles and methodology of planned activities.
The currently applicable legal provisions and also the economic concepts emphasize the importance of circular economy. In this aspect, it is very important to reduce the waste production respectively planning and running a business. Technical research is the key to finding a new applications for waste, in particular disposed on landfilling. Mining and energy industries belong to the biggest producers of waste in Poland. The total share of these two branches in waste production is up to 70% (mining and quarrying 53%; electricity, gas, steam and air conditioning supplay 17%). In environment, economy and social aspect, it is very important to develop this waste. The paper presents research on the physico-mechanical properties of the aggregates based on colliery shale supplemented by fly ash (20% - 40% supplement of fly ash). The following tests should be mentioned among performed: particle size distribution, the sand equivalent test, freeze resistance and direct shear tests. Also the chemical properties found in the literature was invoked. The research shows good physico-mechanical properties of the mixes, such as cohesion (44.62 kPa - 68.57 kPa) or internal firiction angle (34.74° - 40.52°). Though low resistance to weathering and a large susceptibility to frost heave (the mass loss after the freezing cycles is 76%) may limit its applicatin in road engineering. The sand equivalent tests were made only for aggregates. Tested materials shows usefulness for earthen structures. However, the research should be supplemented by chemical tests and also observations of the material properties changes as the effect of time. The research on the leachability of chemical pollutants, which will determine the acceptable share of ash in the mix, could be especially significant. The fact that fly ash contains a lot of sulphates and chlorides, which leach into the environment may pose a threat to living organisms.
Potential sources of rare earth elements are sought after in the world by many researchers. Coal
ash obtained at high temperatures (HTA ) is considered among these sources.
The aim of the study was an evaluation of the suitability of the high temperature ash (HTA ) formed
during the combustion of bituminous coal from the Ruda beds of the Pniówek coal mine as an
potential resource of REY . The 13 samples of HTA obtained from the combustion of metabituminous
(B) coal were analyzed.
The analyses showed that the examined HTA samples varied in their chemical composition.
In accordance with the chemical classification of HTA , the analyzed ash samples were classified
as belonging to the following types: sialic, sialocalcic, sialoferricalcic, calsialic, fericalsialic,
ferisialic.
The research has shown that the rare earth elements content (REY ) in examined HTA samples
are characterized by high variability. The average REY content in the analyzed ashes was 2.5 times
higher than the world average (404 ppm).
Among rare earth elements, the light elements (LREY ) were the most abundant. Heavy elements
(HREY ) had the lowest share.
A comparison of the content of the individual rare earth elements in HTA samples and in UCC
showed that it was almost 20 times higher than in UCC.
The distribution patterns of REY plotted for all samples within their entire range were positioned
above the reference level and these curves were of the M-H or M-L type. The data presented indicate, that the analyzed ash samples should be regarded as promising REY
raw materials. Considering the fact that in 7 out of 13 analyzed ash samples the REY content was
higher than 800 ppm, REY recovery from these ashes may prove to be economic.