不同风化年限的淮南矿区煤矸石理化性质变化规律

Physicochemical property change regularities of coal gangue with different weathering ages in Huainan minging area

堆存于地表的煤矸石在遭受风化以后,其物理和化学性质可在短时间内发生较大变化,这些变化往往具有一定规律。该文选取淮南矿区潘北、潘一及新庄孜煤矿5个不同风化年限的煤矸石采样区进行分层采样。通过对135个样品的相关理化性质测试,对比分析了不同风化程度下煤矸石主要理化性质变化规律。结果表明,煤矸石在电导率、pH值和阳离子交换量等理化性质的变化具有一定规律:随着风化年限的增加,煤矸石电导率与pH值降低,阳离子交换量则不断增高。新鲜煤矸石的3项指标在2a内具有较快的降低速率,其中电导率在2 a内可降低30%,pH值下降接近10%,此后的降低变化速率则较缓慢。阳离子交换量在2 a内可增加17%,在后期的变化中则表现为缓慢上升趋势。在剖面变化特征方面,通过对30和30~60 cm之间的上下两层对比分析发现位于上层的电导率与pH值普遍略高于下层,阳离子交换量则为上层略低于下层。其中p H值的上、下两层的变化差距较小,仅在0.1~0.3之间。煤矸石的电导率、pH值,以及阳离子交换量等3项指标的时空变化均与风化作用的时间或风化程度密切相关。从植物生长条件角度出发,上述理化指标的变化均有利于煤矸石的复垦利用。

Coal gangue is the solid waste from coal mining. Because of weathering, the physico-chemical properties of the coalgangue exposed on the ground＇s surface changes constantly. In order to study the change of coal gangue physico-chemicalproperties under the effects of weathering, the electrical conductivity, pH value and cation exchange capacity, 3 majorphysico-chemical indices are chosen to analyze their change characteristics and general regularities with the weathering timeand the buried depth of coal gangue. The research chooses the distributing area of coal gangue with different weathering age,and divides the research layer into upper layer and lower layer, which are from surface to 30 cm depth and from 30 to 60 cmdepth, respectively. A total of 135 samples from 5 coal gangue hills with different weathering age in Panbei, Panyi as well asXinzhuangzi coal mines in Huainan mining area are collected with the stratified sampling method. The results show that thereare certain change regularities of the physico-chemical properties of the coal gangue. The electrical conductivity and pH valueof coal gangue decrease with the increasing of weathering age. And the cation exchange capacity increases along with theincreasing of weathering age. The 3 indices of fresh coal gangue have a faster decrease rate within the early 2 a. The electricalconductivity reduces by 30% and the pH value falls by nearly 10% within the early 2 a. Then they change slowly. The cationexchange capacity can be increased by 17% within the early 2 a, and then its change grows slower. The change characteristicsof physico-chemical properties of the coal gangue in profile are also obvious. Through the comparative analysis of the upperand lower layers, it is found that the electric conductivity and pH value in the upper layer are generally slightly higher than thatof the lower layer, while the cation exchange capacity in the upper layer is slightly lower than that of the lower layer. Thedifference of pH value between the 2 layers is only from 0.1 to 0.3. The spatial and temporal variations of coal gangueconductivity, pH value and cation exchange capacity are all closely related to the weathering time or the degree of weathering.The great change occurs in the physico-chemical properties of coal gangue exposed to the ground＇s surface within 2 a. It showsthat the weathering is significant. Of course, the temperature effect and hydrolysis as well as other physical processes play therole in the process. Lumpiness decrease of coal gangue due to physical weathering can speed up the change of chemical andother physical indicators. From the angle of the mining area land reclamation, these changes of the physical and chemicalproperties of coal gangue will be in favor of land reclamation in the mining area. The results provide the theoretical basis forland reclamation of coal gangue storage area.