1,355,128 research outputs found
Gli archivi dellʼamministrazione centrale del Regno di Sardegna tra XIV e XV secolo: testimonianze documentarie ed ipotesi di lavoro
No full textL’articolo si pone l’obiettivo di analizzare e ricostruire la politica archivistica aragonese nel Regno di Sardegna, in un arco cronologico che va dal XIV al XV secolo, attraverso lo studio delle fonti documentarie coeve. La conquista del regno negli anni 1323-1324 comportò la riorganizzazione amministrativa dell’isola, con la conseguente creazione di nuovi presidi archivistici. Attestato dal 1327, l’archivio reale del Castello di Cagliari ricevette una sede permanente nel 1332. Dichiarato segreto nel 1334, era l’archivio generale del regno, posto sotto il controllo del maestro razionale di Barcellona e del suo luogotenente in Sardegna, con competenze in materia fiscale. Ma questo non fu l’unico archivio del governo centrale dell’isola: nel 1359 Pietro IV d’Aragona assegnò una sede adeguata alla scrivania dell’Amministrazione generale e al suo archivio, il quale nel XV secolo passò sotto la giurisdizione della Procurazione reale, magistratura cui competeva la conduzione della politica economica dell’isola. Infine, nel 1480 Ferdinando II il Cattolico istituì l’ufficio in capite del maestro razionale di Sardegna e il suo archivio. Questi importanti complessi documentari formarono il nucleo attorno al quale si sarebbe costituito il Regio archivio patrimoniale spagnolo e, in seguito, l’archivio sabaudo. Ciò che principalmente si vuol mettere in risalto nell’articolo è la straordinaria attenzione che la Corona d’Aragona manifestò nei confronti della conservazione documentaria, riconoscendo in essa uno strumento indispensabile per il buon governo e la salvaguardia del patrimonio regio.In this article the author examines and reconstructs the Aragonese archival policy in the Kingdom of Sardinia between the 14th and the 15th centuries, through the study of the coeval documentary sources. The conquest of this kingdom in the years 1323-1324 caused the reorganization of the administration of the island, with the consequent creation of new archives. In that time the Crown of Aragon showed a big care to the preservation of the documents. Attested since 1327, the royal archive of the Castle of Cagliari got a permanent home in 1332. Declared secret in 1334, it was general archive of the kingdom, under the control of the magister racionalis of Barcelona or his lieutenant in Sardinia, with competences in fiscal matters. But this one was not the unique archive of the central government of Sardinia: in 1359 Peter IV of Aragon gave a suitable location to the office of the scribe of the General Administration and to its archive (from 1413 archive of the procurator regius Regni Sardinie), for preserving there the documentation of the Crown Estate in the Kingdom of Sardinia. In the year 1480 Ferdinand II the Catholic established the office of the magister racionalis Sardinie and his archive
Stabilization of mining tailings containing fluospar and heavy metal using potassium dihydrogen and calcium hydroxide
No full textTailings waste from a mineral processing plant of a fluorite and galena mine is characterized by the release of F together with heavy metals such as Zn, Pb, Cd and Cu. Leaching tests carried out on the tailings waste show that the concentrations of F and Pb exceed the legal Italian limits for characterisation as inert material. To avoid the risk of spreading to areas not directly affected by mining activities and to obtain inert products suitable for reuse as construction material or as backfill in the mine, stabilization has been investigated using potassium dihydrogen phosphate singly or combined with calcium hydroxide. In order to assess the effectiveness of the additives for the stabilization of pollutants, reactor batch tests have been carried out by adding different proportions of these additives to the tailings material. The mixture, with a liquid/solid ratio equal of 10, was agitated for 24 hours and, at the end of the test, the eluate was filtered through a 0.45 μm membrane and analysed. The results show that the use of potassium dihydrogen phosphate in combination with calcium hydroxide allows for the immobilization of F and Pb by formation of stable or poorly soluble compounds. In addition, solidification of the thus inertized material using 10 % cement produces a material of which the leachate is in accordance with the regulatory limits for discharge in groundwater, allowing for its use as backfill in the mine
Use of triboelectric Techniques for Separating Feldspar from Quartz
No full textThe paper shows the results of an investigation carried out to enhance the value of two commercial products currently destined for ceramic industry and to beneficiate the non-magnetic fraction of a granite quarry waste, applying electric separation techniques based on triboelectric charging and the use of a free-fall chamber. The test conducted on the k-feldspar/quartz commercial product, with 5,7 % K2O content, shows that is possible to obtain a 9,7 % feldspar concentrate and a quartz product with less than 1 % K2O content, preheathing the feed, without the use of additives. As concern granite quarry waste, the results obtained without the use of additives and pre-treating the feed material with HF and NaOH solutions are compared. It has been found that the pre-treatment with the above mentioned reagents enables to obtain marketable feldspar and quartz products
Electrostatic K-Feldspar/Na-Feldspar and Feldspar/Quartz Separation: Influence of Feldspar Composition
No full textThis paper aims at contributing to the possibility of electrically separating K-feldspar/Na-feldspar and quartz/feldspar, investigating the behaviour of mixtures composed of K-feldspar, Na-feldspar and quartz concentrates. The findings highlight the importance of preheating the material and of interparticle contact. Tests conducted on binary mixtures of K-feldspar/Na-feldspar, K-feldspar/quartz and Na-feldspar/quartz showed that it is possible to achieve satisfactory results in the separation of these species, by triboelectrical charging of the material, preheated to temperatures above 100 °C, using a free fall chamber. Tests carried out on ternary mixtures have demonstrated that additional pretreatment with HF solutions improves the results
Sull’influenza della dimensione delle particelle di flottazione: il caso di un minerale di barite.
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A New Electrostatic Separator For Fine Particles
No full textThe paper deals with the recent achievements resulting from the activity being carried on at the DIGITA and CSGM laboratories of the University of Cagliari, aimed at the development of suitable separation technologies based on the electrophysical properties of mineral components. After a brief review of the problems encountered in the electrostatic treatment of fine particles, the features of a new separator designed in order to overcome the drawbacks of conventional machines are described. Finally some significant results obtained in the course of the development research are given and discussed with reference to the removal of unburned carbon in the beneficiation of fly-ash from coal-fired power stations
Developement of a new electric belt separator for fine particles
No full textThe increasingly restrictive regulations foreseen far landfills and the consequent need to reduce the amount of fly ash to be disposed of in this way, makes beneficiation essential for increasing both the use and value of this by-product. Electrostatic separation offers a potentially promising solution to this problem as with this technique it is possible to treat the hot, dusty fly ash in the dry state. In particular the present paper describes a new separator designed with a view to overcoming the drawbacks of conventional machines. The new separator consists essentially of a grounded metal conveyor belt onto which the particle stream is spread in a thick layer by means of a vibrating feeder. Some signifìcant results of experimental tests carried out on samples collected from Italian power stations are described and discussed
Technico-economical rationalization of a processing plant for barite ores: The case of the Montega Mine, Italy
No full textGoing Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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