铜陵、南陵地区古铜矿冶遗址炉渣的科技研究

Study on the Slags from the Sites of Mining and Smelting in Tongling and Nanling Region

安徽铜陵、南陵地区铜矿资源丰富,古代矿冶遗址数量众多,最早可追溯至二里头文化时期。各遗址遍地分布的炉渣、炉壁等矿冶遗物,为研究中国早期的铜矿冶炼技术提供了大量的实物资料。本工作采用X射线衍射分析(XRD)、X射线荧光分析(XRF)和扫描电镜能谱分析(SEM-EDS)等多种技术手段,对安徽铜陵、南陵地区古铜矿冶遗址的炉渣样品进行检测分析,以了解该地区早期的铜矿冶炼技术。XRD分析结果显示,所检测炉渣样品的物相以铁橄榄石、辉石、钙铁辉石为主,伴有石英、方石英、磁铁矿等矿物,符合炼铜渣的物相特征。根据炉渣的SiO2,CaO和Fe2O3的含量,可将51个炉渣样品分为三大类:Ⅰ类炉渣、Ⅱ类炉渣和Ⅲ类炉渣。其中,Ⅰ类炉渣钙、硅、铁含量较高,其CaO含量远高于Ⅱ类和Ⅲ类炉渣,为铁硅钙系。相较而言,Ⅱ类炉渣为高铁系,其Fe2O3含量明显高于Ⅰ类和Ⅲ类炉渣;Ⅲ类炉渣为高硅系,其SiO2含量较高,钙、铁含量较低。所有炉渣样品的铁含量均高于普通熔炼渣,结合其物相分析结果,可推测全部炉渣为冶炼渣。Ⅰ类、Ⅱ类炉渣的Ca和Fe含量呈现很强的负相关性,且波动范围很大,显示二者的含量并非人工调控,更可能是来自矿石中的天然成分。据此可以推测,本地区的早期工匠可能尚未认识到含钙和含铁助熔剂的作用,没有掌握不同类型铜矿石的配矿技术。SEM-EDS的分析结果表明,炉渣中的金属颗粒夹杂以冰铜、红铜和砷铜为主,表明该地区同时存在红铜和砷铜的冶炼活动。不同品位的冰铜颗粒大多来自不同遗址,尚没有在同一遗址发现较多品位依次升高的冰铜颗粒,因而难以确认冰铜熔炼环节的存在,不能证明上述遗址是否已采用了“硫化铜矿-冰铜-铜”的冶炼技术。所发现的冰铜颗粒,可能是采用硫化铜矿死焙烧工艺或混合矿原料冶炼的结果。铜陵夏家墩遗址炉渣中砷铜颗粒的存在,表明该地区早至西周时期,很可能已掌握了采用共熔还原法冶炼砷铜的技术。相关研究结果,对探讨砷铜技术的起源和传播,以及中国早期冶金技术的发展和生产组织状况均具有重要意义。

Tongling and Nanling region is abundant in copper ore resources.From the 1980s,a large number of the sites of mining and smelting have been found in this region,the earliest of which could date back to the Erlitou period.Slags,furnace walls and other smelting remains from the sites of mining and smelting provided a good deal of archaeological materials for the study of the smelting technology of copper ore in ancient China.Slag samples collected from the smelting sites in Tongling and Nanling region,Anhui Province were analyzed by means of X-ray diffractometer(XRD),X-ray fluorescence spectrometer(XRF)and scanning electron microscope with energy-dispersive X-ray spectrometer(SEM-EDS)to understand the smelting process of copper ore.The results of XRD showed that the main phase compositions in the slag samples included fayalite,augite and hedenbergite, accompanied with quartz,cristobalite and magnetite,et al.,which corresponded with the phase characteristics of copper smelting slag.From the contents of SiO2,CaO and Fe2O3,all slag samples were divided into three groups:TypeⅠ,TypeⅡ and TypeⅢ.The TypeⅠ was Iron-Silicon-Calcium slag,which was high in the contents of calcium,iron and silicon.The calcium contents of the TypeⅠslag were much higher than those of the TypeⅡand the TypeⅢslag.The TypeⅡ was iron-rich slag,and its Fe2O3contents were higher than those of the TypeⅠand the TypeⅢslags.The TypeⅢ was silicon-rich slag which was higher in SiO2contents and lower in the calcium and iron contents.The Fe2O3contentsin all slags were higher than the common melting slags.Combined with the results of XRD,it was concluded that all slag samples are from the smelting process of copper ores.Calcium and iron levels in the TypeⅠand TypeⅡslags vary obviously and show the significant negative correlation,which indicated that calcium and iron in the slags was not controlled artificially and it is very possible that the calcium and iron in the slags were from the copper ores.Based on the contents of calcium and iron,it could be inferred that the early craftsmen in the Tongling and Nanling region didn’t seem to understand the effects of calcium-bearing flux and iron-bearing flux and master the technology of matching ore of different kinds of copper ore.According to the results of SEM-EDS,the metal prills in the slags mainly included matte,copper and arsenic bronze,which showed that the smelting activities of copper and arsenic bronze coexisted in Tongling and Nanling area.The matte prills in the slags were mainly from different sites of mining and smelting,and the matte prills with the increasing copper content in turn were not extensively found in the same sites of mining and smelting.Therefore it was difficult to certify the existence of the matte smelting process,and it was not verified whether the smelting process of“copper sulfide ore-matte-copper”has been widely used in this area in the Pre-Qin Period.The matte prills in this work were possibly produced by the dead roasting process of copper sulfide ores or cosmelting process of the copper sulfideoxide ore.On the basis of the arsenic bronze prills in the slag of Xiajiadun site,we could draw a conclusion perhaps that the ancient craftsman in this area mastered the cosmelting technology of arsenic copper in the Western Zhou period.The research results have an important significance for the study on the origin,the development and production mode of early smelting process in ancient China.