PB块和海南块在承钢4#高炉冶炼中的应用

研究了承钢4#高炉常用的两种天然块矿的冶金性能,以及配吃不同块矿对高炉冶炼的影响。研究发现:PB块的热爆裂性能和荷重软化性能较海南块差,还原性和还原粉化强度要高于海南块;单独配吃PB块和按一定比例配吃混合块矿后,高炉的经济技术指标较好,透气性及出铁状况良好,吨铁成本低;单独配吃海南块后,高炉的经济技术指标差,平均透气性明显下降,出铁不稳,频繁出现憋渣铁现象,吨铁成本提高;配吃混合块为承钢4#高炉的最优选择。

南非块矿与PB块矿质量对比分析

矿石的化学成分、物理性能和冶金性能分析表明,PB块矿与南非块矿相比,含铁品位相当,SiO2、Al2O3、S和碱金属含量低,但P含量高,烧损大;PB块矿的粒度、冷热强度均不如南非块矿;PB块矿还原性明显优于南非块矿62.7%。鉴于PB块矿的性能,建议高炉使用时将PB块矿布在高炉中心,减少低料线操作,采取矿焦混装等措施,以改善料柱透气性。

青岛特钢高炉使用PB块和纽曼块对比分析

对青岛特钢高炉使用的PB块矿、纽曼块矿的化学成分、冶金性能及使用效果对比分析。两种块矿化学成分相差无几,PB块矿的热爆裂性、还原性略优于纽曼块矿,纽曼块矿的荷重软熔性略优于PB块矿。使用两种块矿后,高炉经济技术指标统计分析可知,纽曼块矿对高炉稳定顺行未有不利影响,高炉可以使用纽曼块矿代替PB块矿。

Geochemistry and Zircon U–Pb age of the Yao＇an pseudoleucite porphyry,Yunnan Province,China

The Yao'an Pb–Ag deposit, located in the Chuxiong Basin, western Yangtze Block, is an important component of the Jinshajiang–Ailaoshan alkaline porphyry–related polymetallic intrusive belt. This complex suite of rock bodies includes a vein of pseudoleucite porphyry within deposits of syenite porphyry and trachyte.The pseudoleucite is characterized by a variable greyish,greyish-white, and greyish-green porphyritic texture. Phenocrysts are mainly pseudoleucite with small amounts of alkali feldspar and biotite. In an intense event, leucite phenocrysts altered to orthoclase, kaolinite, and quartz.Both the pseudoleucite porphyry and the syenite porphyry samples were typical alkali-rich, K-rich, al-rich rocks with high LaN/YbNratios; enriched in light rare earth elements and large-ion lithophile elements, and depleted in high field strength elements; and with strongly negative Ta, Nb, and Ti(TNT) anomalies and slightly negative Eu anomalies—all characteristics of subduction-zone mantle-derived rock.We obtained a LA-ICP-MS zircon U–Pb age of 34.1 ± 0.3 Ma(MSWD = 2.4), which is younger than the established age of the Indian and Eurasian Plate collision.The magma derived from a Type-II enriched mantle formed in a post-collisional plate tectonic setting. The geochemical characteristics of the Yao'an pseudoleucite porphyry are powerful evidence that the porphyry'sdevelopment was closely linked to the Jinshajiang–Ailaoshan fault and to the Indian-Eurasian collision.

Forming Proterozoic basement within eastern Central Asian Orogenic Belt:Evidence from zircon U-Pb-Hf-O isotopes

As part of the mosaic of micro-continents within the Central Asian Orogenic Belt(CAOB), the Xing’anAirgin Sum Block(XAB) features increasingly-recognized Meso-Neoproterozoic geological records. However, the origin, temporal-spatial distribution of ancient materials, and their roles in crust evolution remain to debate. This paper presents an integrated study of zircon U-Pb ages and Hf-O isotopes for Mesoproterozoic and Paleozoic granites from the Erenhot region of central Inner Mongolia, along eastern CAOB. The intrusion of 1450 Ma syenogranite denotes that the Precambrian basement of XAB extends from Sonid Zuoqi westward to Erenhot. The 384 and 281 Ma monzogranites containing Mesoproterozoic xenocrystic zircons possess Proterozoic-dominant two-stage Hf model ages, further suggesting the wide existence of Proterozoic crust beneath western XAB. Cyclic Proterozoic crustal growth and reworking seem to show close linkages with the orogenesis during relevant supercontinent cycles. 1450-1360 Ma juvenile crustal growth at Erenhot and synchronous ancient crust reworking at Sonid Zuoqi and Abagaqi were likely resulted from retreating subduction involved in Columbia breakup, while 1.2-1.0 Ga reworking and 0.9-0.7 Ga growth events within the Erenhot basement might respond to assembly and breakup of Rodinia, respectively. Besides, our work confirms that reworking of Neoproterozoic crust played important roles during Paleozoic multi-stage accretion of CAOB.

U-Pb zircon age and Hf isotope compositions of Mesoproterozoic sedimentary strata on the western margin of the Yangtze massif

The Mesoproterozoic sedimentary strata on the western margin of the Yangtze massif are a clastic-carbonate rock association intercalated with a small amount of tuff and basalt and deposited in a relatively stable environment. They are termed as the Kunyang Group, the Huili Group, and the Dongchuan Group respectively in different regions. We performed zircon U-Pb da- ting of the tuff from the groups. The results, coupled with the detrital zircon U-Pb ages of clastic rocks from the Kunyang Group and the Dongchuan Group, indicate that the sedimentation ages of the Kunyang Group and the Huili Group range from 1050 to 1000 Ma and that the Kunyang Group and the Huili Group belong to a sedimentary association with contemporaneous heterotopic facies. The detrital zircon ages and Hf isotope compositions reveal that the clastic materials in the Kunyang Group and the Huili Group are derived primarily from the Cathaysia massif. Zircons of the tuff in the Dongchuan Group yields an age of ca. 1.5 Ga and all the zircon ages of clastics in the Dongchuan Group are older than 1.5 Ga, indicating that the sedimentation of the Dongchuan Group occurred during the late Mesoproterozoic Changcheng Period. Age spectra of the detrital zircons in- dicate that the clastic materials of the Dongchuan Group are derived primarily from the ancient basement of the Yangtze mas- sif. A systematic Hf isotope determination of various types of zircons in the above three stratigraphic units shows that there is a rapid elevation in the initial Hf value of zircon at -1.5 and 1.0 Ga. Previous studies on the sedimentary characteristics of the Kunyang Group and the Huili Group show that both were deposited in a foreland basin. Combining our data with previous studies, we suggest that the Kunyang Group and the Huili Group are foreland basin sedimentary successions formed along the southern side of the Yangtze massif after an amalgamation between the Yangtze massif and the Cathaysia massif during the Grenvillian. The assembly of the Yangtze massif and the Cathaysia massif developed gradually from the west to the east and was finally completed in the eastern segment of the Yangtze massif at 0.9 Ga, representing the last stage of the Rodinia super- continent assembly, Hf isotope compositions in zircon indicate that the supercontinent cycle has an intimate relation with crus- tal growth.

Geochronology,petrology,and geochemistry of the Yaojiazhuang ultramafic-syenitic complex from the North China Craton

The Yaojiazhuang ultramafic-syenitic complex is one of the representative Triassic alkaline plutons on the northern margin of the North China Craton （NCC）. Based on detailed study of the zircon U-Pb age, petrological, mineralogical, and geochemical data of the complex, the characteristics of the magmas system, the petrogenesis of different rock types, and the nature of the mantle source were discussed to provide new constraints on the origin and tectonic setting of the Triassic alkaline belt. Cumu- lus ultramafic rocks, clinopyroxene-syenites and syenites are the main rock types of the complex. The zircons from the sye- nites yielded a U-Pb age of 209 Ma. Diopside-augite, biotite, and sanidine-orthoclase are the major minerals, with subordinate apatite and magnetite. Rocks from the complex are enriched in large ion lithophile elements （LILE） and light rare earth ele- ments （LREE）, depleted in high field strength elements （HFSE） and heavy rare earth elements （HREE）, and the initial 878r]86Sr ranges from 0.7057 to 0.7061 and eNd（t） from -9.4 to -11.4. Mineralogy and geochemical data demonstrate that the parent magma of the complex is SiO2-undersaturated ultrapotassic alkaline-peralkaline, and is characterized by high CaO content and fluid compositions （P205, CO2, H20）, and by high oxygen fugacity and high temperature. The complex was originated from a phlogopite-clinopyroxenite-rich lithospheric mantle source in the garnet-stable area （〉 80 km） that had previously been meta- somatized by melts/fluids from altered oceanic crust. The parent magma has been contaminated by little ancient TTG gneisses during magma emplacement. The development of the Yaojiazhuang complex indicates that the northern margin of the NCC has entered into an extensively extensional regime in the Late Triassic.