Test and Research on Hydraulic Tailings Backfilling in Liaoning Wulong Gold Mine

1. Brief Introduction to the Achievement
Based on the situation of Sidaogou Sub-mine which is located in Dandong City where land and forest resources are limited, existing proven theory and technology of hydraulic backfilling and laboratory simulating tests were taken as references to engineering design and research. Some new techniques, new methods and new materials were applied in the engineering construction and the commercial test of the backfilling system, in order to build up a set of rational backfilling processes with less land occupation, no forest resource losses, better use of the tailings, low capital cost, reliable operation, and economical performance.

The technical characteristics of this project are：

Applying the principle that the dewatering rate of backfilling follows the Darcy Rules, theoretical analyses of the research on forced dewatering under negative pressure were carried out to find out the main factors that influence the negative pressure. Forced negative pressure dewatering system, a high efficiency negative pressure box with infiltration bellowpipe, was adopted. And new technologies and processes, the clearing system for the filtering materials and the wooden structure enclosure wall, were also used.

Due to back filling is applied in Sidaogou Sub-mine, it has low level requirements for filling strength, taking use of which a filling system with following characteristics was built: the filling system operates interlockingly with the processing plant, without sand bin and agitating barrel. And the ready filling material is directly sent to the transporting pipelines, with the upper mouth of the pipelines being equipped with a water adding pipe that is at acute anle(20) with the tailings pipeline which use high pressure water jet to mix the filling materials evenly before transportation.

Tower crane and rope lift was used to lay the filling pipelines, which avoided uses of land and trees, and shortened the transportation distance and improved the transportation conditions.

2. Techno-economical Indices and Benefits
Actual operation indices of Wulong Gold Mine is as the following:

The capital cost for the whole filling system saves over 500,000 yuan comparing with the conventional technology.

It yeided a direct economic profit of 3,015,000 yuan.

60% of the tailings is filled into the mine goaf, which may double the service life of the tailings dam. Deducting the expenditures for filling (the expenses for 6 years’ filling to be 806,700 yuan), its economic profit was as much as 9,990,000 yuan.

Using tailings to fill the mined out areas can release ground stress, improve the safety conditions of the mine area, and reduce amount of production waste from the mine, i.e., less tailings and less environment pollution.

3. Comments and Application Peospects 评价及推广应用
In the test and research on hydraulic tailings back filling, the filling technique is practical and advanced; laying filling pipelines by tower crane and rope lift reduced the engineering, avoided land use; using steel cable to put down the fixed filling pipelines saved engineering and materials, and shortened the working period; the application of negative pressure dewatering technology being applied in mine goaf filling was the first home and abroad. The test and research parameters would speed up the process of dewatering, create conditions for continuous filling. So the above technology can be applied in similar techniques.