Heishan Iron Mine, Chengde City, Hebei Province

Heishan Iron Mine, located in Gaositai Town, Chengde County, Chengde City, Hebei Province, is an important "Damiao" magmatic iron deposit in northern China. The accumulated proven reserves of iron ore resources in the mining area exceed 1× 108t, accompanied by elements such as vanadium, titanium, cobalt, nickel and platinum group.

The mining area is located in the northern margin of North China Platform, at the junction of Yanshan Platform Fold Belt and inner mongolian axis, and belongs to Damiaoqiong Fault Bundle (Grade IV) structural unit in the fault uplift area on the edge of Platform Fold Belt. The metallogenic belt belongs to the iron-copper-molybdenum-lead-zinc-silver-manganese-uranium-phosphorus-coal-bentonite metallogenic belt in the eastern part of the northern margin of North China block. There are a large area of plagioclase complexes along the east-west and northeast main faults of Damiao, and Damiao-type iron deposits are closely related to plagioclase and syenite of basic complexes.

1. Brief description of mine geology

(1) stratum

The strata exposed in the mining area are mainly Neoarchean Dantazi Group metamorphic rock series, Proterozoic metamorphic plutonic rocks, Mesoproterozoic carbonate-dominated sedimentary rocks, Mesozoic Jurassic-Cretaceous volcanic and continental clastic sedimentary rocks, and Quaternary alluvial and diluvial deposits.

(2) Structure

Heishan iron deposit is located in Damiao plagioclase complex, and its mineralization is closely related to plagioclase complex and mainly controlled by the secondary structure of Damiao complex. There is a Fengning-Longhua deep fault in the north, and a Hongshilai-Damiao deep fault in the south, which is subjected to NE and NW compression and torsion. At the same time, a group of nearly north-south extensional fractures and fractures are produced, which control the output of syenite and iron ore bodies. Heishan Iron Mine is located in the north of Wangying Village, which is located in the secondary compression-torsion structure of Hongshilai-Damiao deep fault. According to the metallogenic relationship with iron ore, the structure can be divided into three stages: before mineralization, during mineralization and after mineralization.

(3) Magmatic rocks

The basic complex exposed in the mining area is mainly composed of a large area of plagioclase ((kloc-0/726 9) ma) and sporadic syenite ((kloc-0/693 7) ma), and a small amount of diorite porphyry, olivine pyroxenite and amphibole rocks are distributed along the fault. Plagioclase, syenite and iron ore slurry are homologous, plagioclase and syenite are diagenetic first, and iron ore slurry is infiltrated later. There are differentiated disseminated ore bodies in some syenite bodies, and the ore bodies in the contact zone between syenite and two rock bodies are through ore bodies.

2. A brief description of the characteristics of the deposit

(1) ore body characteristics

Heishan iron mine is a typical representative of magmatic intrusive iron mines in China, including No.1, No.2, No.3, No.6 and No.8 orebodies, Dongdawa iron mine section in Longtangou-Yaqing subway mining area, No.72 and No.73 orebodies. The ore bodies in the mining area are mainly lenticular vanadium-titanium magnetite, which are produced in groups and are mostly blind ore bodies. Ore bodies are mainly vein-like and dendritic. At the intersection of faults, it appears locally in the shape of mineral capsules and radishes. ①, ② ore bodies, ore bodies in Dongdawa ore section, ③, ⑥ and ⑧ ore bodies are all controlled by the Heishan-Longtangou compression-torsion structural belt. The ore bodies are echelon-shaped on the left side in the plane and obliquely arranged in imbricate shape in the vertical direction, and the extension depth of the ore bodies is greater than the extension length.

The samples were collected from No.2 ore body in the mining area, distributed between 0 and 28 exploration lines, and composed of No.2-1,2-2, 2-3 and 2-4 ore bodies. ②-4 orebody has been extinguished at the elevation of 650m, and a few single orebodies extend below the elevation of 200m m.. ②- 1 ore body is the main ore body of ② ore body group, with a large extension, and its characteristics are briefly described as follows:

②- 1 ore bodies are distributed between 0 ~ 36 exploration lines, and the controlled length of ore bodies is 350m ... The ore bodies are exposed on the surface with an elevation of 900m, the maximum extension depth is on the 12 line, the elevation is-139m, and the inclined extension depth reaches1040m ... When the altitude is above 100 meters, they often contract and expand to form mineral capsules. ②- 1 The shape of the lower part of the ore body is relatively simple, and it can be divided into 5-6 ore bodies according to different elevations and positions. ② 1 The average thickness of the lower part of the ore body is 33.46m, and the average grade of the ore body is TFe34.27%, mFe 19.93%, V2O50.350% and TiO28.56%. Occurrence of ore body: strike 65 NE, dip southeast, dip angle 50 ~ 60. From line 28 to line 12, with the increase of extension depth, the number of ore layers, thickness and grade decrease.

(2) Ore type and structure

The natural types of ore can be divided into three types according to ore structure and iron mineral content: ① dense massive iron ore with iron mineral content greater than or equal to 60%; ② Dense disseminated iron ore with iron mineral content of 30% ~ 60%; ③ Sparse disseminated iron ore with iron mineral content of 12% ~ 30%. Ores can be divided into two types according to TFe content: massive iron ore with TFe of 35% ~ 60%; TFe of disseminated iron ore is 15% ~ 35%. The ore is vanadium-bearing titanium iron ore with complex composition, which belongs to weak magnetic iron ore and needs to be beneficiated.

Ore structures mainly include authigenic-semi-authigenic granular structure, lattice dissolution structure and sponge meteorite structure. Ore structures are mainly dense massive structures, dense disseminated structures and sparse disseminated structures.

Specimen name Vanadium titanomagnetite ore number DB007 Stratigraphic age Precambrian

Atlas of large ore specimens from typical mines in China

The ore specimen was collected from No.2 ore body in the mining area. The surface of the sample is iron black, with giant crystal structure and dense block structure. The ore minerals are mainly vanadium-titanium magnetite and ilmenite, followed by pyrite and chalcopyrite. Gangue minerals mainly include chlorite and plagioclase. The TFe grade is ≥30%, and the TiO2 grade is 3. 1%.

Genetic types of Heishan iron mine in Chengde City, Hebei Province Late magmatic infiltration genesis