GB/T 43933-2024Technical specification for land reclamation and ecological restoration of metal mine (English PDF)

3 Terms and definitions

Mine land reclamation and ecological restoration is defined as the activity that, for the geological environment damage, land destruction and vegetation damage caused by the extraction of mineral resources, relies on human support and guidance together with natural restorative capacity and takes preventive and restorative measures so that the mine geological environment becomes safe and stable, the destroyed land is reclaimed for use and the ecosystem function is restored or improved; a note abbreviates it to reclamation and restoration. A reference ecosystem is an ecosystem that can serve as the target or benchmark of ecological restoration, a note adding that it usually includes the ecosystem before damage, a local ecosystem not degraded by human activity, and an ecosystem able to adapt to ecological and environmental change that is occurring or can be foreseen. Land destruction is the process and state in which the original function of the land is partly or wholly lost through mine production and construction activity.

The site terms defined are the open pit, the mining site where the mineral is extracted after the overlying rock and soil have been stripped; the waste dump, the site where the rock and soil stripped in open-pit mining and the waste rock from underground workings are heaped, also called a spoil dump or rock dump; the tailings reservoir, the place formed by damming a valley mouth or enclosing ground, used to store the tailings discharged after ore dressing; the heap leaching site, the place where the ore is heaped and low-grade metal extracted by drip or spray leaching; and the in-situ leaching site, the leaching ground where metal minerals are extracted by in-place leaching or by in-place leaching through underground boreholes. Ground surface movement area is the range affected by the horizontal and vertical displacement of the surface caused by the goaf formed by underground metal mining.

Natural restoration is defined as stopping human disturbance of the ecosystem so as to lighten the load, and relying on its self-regulating and self-organizing capacity to let it succeed and renew itself in an orderly direction. Landform reshaping is forming a new landform in harmony with the surrounding landscape, by orderly dumping and land shaping, on the basis of removing geological environment problems and controlling latent pollution risk and soil erosion hazard, according to the way the mine landform has been damaged and the degree of destruction and taking account of the original relief. Soil reconstruction is the reconstitution of the soil matrix on destroyed mine land by engineering, physical, chemical and biological measures so as to form a soil profile structure and fertility fit for vegetation growth. Vegetation reconstruction is the rebuilding of a lasting and stable plant community by selecting pioneer and site-adapted species and carrying out their arrangement, planting and tending, having regard to climate, altitude, slope, aspect, the composition of the surface material and the thickness of the effective soil layer. Landscape construction is the building of an ecosystem in harmony with the surrounding landscape, following the integrated protection and restoration of mountains, rivers, forests, farmland, lakes, grassland and sand, and taking full account of the structural adjustment and optimal allocation of land, water, biological resources and the human settlement environment during the reintegration of the point, line, area and network landscape of the mining area. Adaptive management is the method and process of gaining experience by monitoring and assessing the management and practical measures already taken and of correcting and improving them as the ecosystem changes.

4 General requirements and basic principles

4.1 The metal mine site and the surrounding ecosystem are to be treated as one whole. On the basis of the importance of the ecosystem function of the place where the mine lies, of the human settlement environment and of economic and social development, and having regard to natural conditions, relief, the ecological and environmental problems of the mine and their degree of harm, the concept of integrated protection and systematic treatment of mountains, rivers, forests, farmland, lakes, grassland and sand is to be held to; areas of the mine site that can be restored are to be reclaimed in good time during extraction, following the laws of ecological succession and the inner mechanism of the ecosystem, so that with sound techniques and models the geological environment of those areas becomes stable, the destroyed land is reclaimed for use, ecosystem function is restored and raised, the biodiversity of the mining area is recovered, green mine construction is advanced and harmony between people and nature is achieved.

4.2.1 Protection first and control at source. The siting and alignment of metal mine land and the design of the production process system are to be optimized so that the effect on sensitive targets such as basic farmland, basic grassland, important protected species, protected areas, water sources and cultural relics is reduced at the source; sound source control measures are to remove geological environment hazards and control environmental pollution and soil erosion so that a safe, stable and pollution-free state is reached; and engineering, biological and chemical reclamation measures are to restore the damaged ecosystem.

4.2.2 Unified planning and coordinated implementation. The targets, direction, standards and measures are to be aligned with territorial spatial planning, mineral resource planning, territorial ecological restoration planning and the mineral resource development and utilization plan, and to be in harmony with the current land use and the surrounding landscape; the reclamation design is to be unified with the mining design and its technical measures and timing closely combined with the extraction process, so that over the whole life of the mine extraction and reclamation proceed together and, along with green mine construction, mitigation and protection, preventive control and reclamation measures are taken in step, so that the geological environment is treated in good time, the destroyed land is reclaimed and ecosystem function is restored, with the best restoration effect and the best state of use sought.

4.2.3 Combination of human restoration and natural recovery. According to the geological stability of the mine, the suitability for reclamation and the ecological resilience, the principle of tillage where tillage is fit, forest where forest is fit, grassland where grassland is fit, wetland where wetland is fit, waste where waste is fit and sand where sand is fit is to be held to; the damaged ecosystem is to be restored by human measures of mitigation and protection, preventive control and reclamation, while respecting, conforming to and protecting nature and making full use of natural restorative capacity, so that the composition and structure of the local biological community are gradually restored and the restored ecosystem becomes self-maintaining and self-regulating.

4.2.4 Systematic treatment and functional improvement. The reclaimed land is to be aligned with territorial spatial planning, mineral resource planning and territorial ecological restoration planning, and through whole protection, integrated treatment and systematic restoration the geological environment is to become stable, the destroyed land reclaimed and ecosystem function restored; planning and implementation are to follow the requirements of biodiversity protection, which is to be carried through the whole process by way of landform reshaping, soil reconstruction, vegetation reconstruction and landscape construction.

4.2.5 Public participation and monitoring throughout. Over the whole life of mine development and reclamation, contact with the stakeholders is to be kept up and they are to be given active and meaningful opportunities to take part, so that the drafting, implementation, monitoring, evaluation and adaptive management of the plan reflect their views, and progress is to be reported and updated to them so that fairness and inclusiveness are ensured. The stakeholders include the land users, communities, government, regulators and enterprises within the mine area, together with investors, industry peers, academia and the media; local traditions, customs, social expectations and the vision of the enterprise are to be respected, so that the benefit to the local community, the environment and the mining industry is maximized.

6 Baseline survey and problem identification and diagnosis

6.1 The baseline survey covers natural conditions, the socio-economic and cultural setting, mine production and construction, the current geological environment, land destruction and reclamation, and ecological status. Natural conditions cover geographic position, relief, climate, hydrology, the regional geological outline, regional hydrogeology, soil condition, soil erosion and animal and plant resources. The socio-economic survey covers the population, agricultural population, arable land per head and production conditions of the last three years for the villages inside the mine area and the neighbouring villages affected; the cultural survey covers geological heritage, cultural relics and monuments, ancient villages and historical and cultural conservation sites. The survey of production and construction covers the nature of the enterprise, the extraction limits, the mining method, the production process, the scale of production, the service life or remaining life, the extraction programme and the general layout.

6.1.4 The survey of the current geological environment covers stratigraphy and lithology, geological structure, hydrogeology, engineering geology, mine geology and adverse geological phenomena, following DZ/T 0223. The survey of geological environment damage at the mine site covers the distribution, scale, structure, degree of development, degree of harm and triggering factors of collapse and landslide in the open pit; of goaf subsidence, ground fissures, ground settlement and other surface rock movement in underground workings; and of landslide at in-situ leaching sites, waste dumps, heap leaching sites and tailings reservoirs. The survey of the current soil and water environment covers soil and groundwater pollution at the mine site, soil pollution following HJ 25.1 and HJ 25.2 and groundwater pollution following HJ 25.1, HJ 25.2 and HJ 164. The survey of potential pollution risk covers, for the open pit, the mineral composition and chemical composition of the ore and the inflow and quality of pit water; for underground workings, the mineral and chemical composition of the ore and the inflow and quality of underground water; for the in-situ leaching site, the leaching process, the washing measures and the quality of the tail water; for the waste dump, the solid waste attribute of the waste rock, the quality of the leachate, the impervious measures and the closure barrier measures; for the tailings reservoir, the solid waste attribute of the tailings, the quality of the discharged and seepage water, the impervious measures and the closure barrier measures; and for the heap leaching site, the solid waste attribute of the residue, the quality of the seepage water, the impervious measures and the washing measures.

6.1.5 The survey of land destruction and reclamation covers land use and tenure, so that the type, quantity and quality of land use and the tenure situation are made clear and the distribution of arable land and basic farmland is surveyed; undamaged land, chiefly the land use type and area, the soil type, the effective soil thickness, the soil profile and the physical and chemical properties, the land use type following GB/T 21010 and TD/T 1055-2019; damaged land, chiefly the open pit, the underground goaf, the waste dump, the tailings reservoir, the heap leaching site, prospecting remains and the surface movement area, the survey covering the area, land class, damage type and degree and following TD/T 1049; and land already reclaimed, the survey units being divided by reclamation direction, time, position and measures and covering soil quality, productivity level and ancillary facilities, following TD/T 1049.

6.1.6 The survey of ecological status is to extend over the mine area together with the catchment, mountain range, hydrological unit and ecological unit in which it lies, so as to cover the area affected by metal mining. It covers the community features of the ecosystem, including the species composition and features of the animal and plant communities, in particular the species, numbers and habitat of important species such as the zonal vegetation constructive species, pioneer species, local key species, indicator species and alien invasive species; the protected objects, functional zoning and protection requirements of nature reserves, world natural heritage sites, the ecological conservation red line and other important sensitive areas; the species, numbers and habitat of the species listed in the national and local lists of protected wild animals and plants and of old and famous trees; and, for land already destroyed, the state of ecological degradation, including the damage to the original ecosystem structure and the difficulty of artificial restoration.

6.2 Problem identification and diagnosis. The analysis of geological stability, aquifer damage, damage to the relief and landscape and damage to land resources at the mine site is to follow DZ/T 0223, printed in the clause as DT/Z 0223. The potential pollution risk of the mine site is judged from the solid waste attribute of the waste rock, tailings and heap leaching residue together with the quality of the seepage water at the site. Where the stored solid waste is hazardous waste or class II general industrial solid waste and the concentration of any characteristic pollutant in the seepage water exceeds the maximum permitted discharge concentration of GB 8978, the first-grade standard applying to class II pollutants, the potential pollution risk of the site is serious; where no characteristic pollutant exceeds that concentration but a pollutant exceeds the class III water quality standard of GB 3838, the risk is relatively serious; and where no characteristic pollutant exceeds the class III standard of GB 3838, the risk is slight. Damage prediction identifies from the baseline survey the important protected species, important ecologically sensitive areas and cultural resources, and predicts from the production programme the geological environment damage, potential pollution risk, land destruction, vegetation damage, ecological degradation and water resource damage that the area to be destroyed may suffer. Diagnosis then analyses the causes and screens out the ecological problems of serious grade, which are to be discussed separately when the reclamation plan is prepared.

9 Execution of the works

9.1 Protective measures. Avoidance requires that the distribution and protection requirements of sensitive targets such as basic farmland, basic grassland, public welfare forest, protected areas, water sources, the ecological conservation red line and cultural relics in and around the mine be established, and that mine works avoid the several kinds of sensitive area and meet the management requirements of protected areas, of the ecological conservation red line and of water source areas together with the control requirements of territorial spatial planning. Mitigation requires that the effects during the construction and production stages be identified and predicted and a reasonable and workable engineering scheme adopted, with measures to prevent or lessen adverse effects, to reduce harm to animals and plants and the occupation of habitat, to control surface deformation and to protect groundwater; that where several open-pit workings are suitable the extraction order be optimized and, where no mineral is covered, the worked-out pit be used to store waste rock and tailings so that new land occupation is reduced; that underground extraction preferably use a filling method so that surface deformation is reduced and ground collapse and fissures avoided; that in-situ leaching of ion-adsorption rare earth ore avoid areas of severe adverse geological phenomena, reliable treatment being applied to poor engineering geological conditions so that leakage of the leaching agent does not cause geological environment problems; that waste dumps, tailings reservoirs and heap leaching sites preferably be designed with gentle slopes so that slope reduction is not needed at reclamation, with interception and drainage on the crest and face so that gullies do not form; and that linear works such as pipelines and roads build ecological corridors for species migration and gene exchange so that the barrier effect is reduced. Protection of important species and cultural assets requires that, where mine construction and production adversely affect key protected wild plants, endemic plants or old and famous trees, the layout be optimized and in-situ or ex-situ protection and closer observation applied, all specimens that can be transplanted and are in good condition preferably being transplanted; that, where key protected wild animals, endemic animals or their habitats are affected, the construction scheme and the mode of operation be optimized, species rescue carried out and the habitat protected; and that fencing, warning signs and reinforcement protect geological heritage and cultural landscapes of major scientific and cultural value.

9.2.1 and 9.2.2 Comprehensive utilization of solid waste and use of species. Valuable components in waste rock and tailings are preferably recovered first, after which the waste rock and tailings are used as resources for backfill, road building and building materials. Valuable components in heap leaching residue are likewise preferably recovered; residue without recovery value is to be rendered harmless so that the latent pollution risk is removed before it is used as backfill, road material or building material. Species collection means gathering the several kinds of propagating material of local plants, in particular important species such as the zonal vegetation constructive species and local key species; species use means making the greatest possible use of the collected local plants in vegetation reconstruction so that the local germplasm resource is protected.

9.2.3 Topsoil stripping, stockpiling and use. Stripping follows the rule of stripping all that can be stripped: the stripping of topsoil is to be arranged for the disturbed areas covered by the production programme, and the thickness, area and volume computed, the thickness being settled together with the effective soil thickness found in the land survey. Weathered rock and soil within the mine site that can serve as a soil source for reclamation is to be stripped separately. Following the rule of stripping by zone, by stage and by layer, the change of land destruction in space and time is to be predicted from the excavation and stripping programme of the open pit, the dumping programme of the waste dump, the leaching programme of the heap leaching site, the tailings discharge programme and the flooding limits of the reservoir, and a zoned and staged stripping programme drawn up. Spoil from the drilling of injection holes at an in-situ leaching site is treated as topsoil and preferably stored in bags. For high-altitude and cold mines, stripping and preservation are to be combined with turf stripping, tending and re-covering. Where the plough layer is stripped for use, TD/T 1048 applies. Stripping is to protect and use the surface vegetation and the remaining biota, and the vegetation naturally recovered on land already destroyed is likewise to be protected and used. Stockpiling follows the rule of stockpiling by zone, near the site and for use near the site: the area and the duration of storage are to be made clear, the stockpile site chosen where soil erosion and geological hazards will not be caused and preferably not on arable land; topsoil is to be stored separately and by layer, apart from weathered rock and soil; excessive compaction by machinery and other activity that damages the properties of the topsoil is to be avoided; retaining, covering and drainage measures are to be taken; and where storage lasts longer than one growing season, grass sowing or turf laying is to be applied. Use follows the rule of using what is stripped at once and backfilling layer by layer, the topsoil being used first for the soil reconstruction of areas reclaimed during the production period.

9.2.4 Removal of stress factors. Geological environment damage is to be treated before reclamation work begins, with monitoring and early warning strengthened. Collapse of open-pit slopes is preferably controlled by slope cutting, propping, anchoring, protective netting, rockfall benches, retaining walls, concrete grid slope protection, closed concrete grouting and interception and drainage works. Landslide at the open pit, the waste dump, the tailings reservoir, the heap leaching site and the in-situ leaching site is preferably controlled first by drainage, combined with load reduction, toe buttressing, anchoring and retaining and grouting reinforcement, following GB/T 38509. For underground extraction, measures against surface rock movement are chosen according to the mining method: with filling methods the strength of the fill and the contact ratio with the roof are to be ensured, surface fissures backfilled in good time and the original land use restored, and the surface movement area observed and assessed over the long term; with open stoping and caving methods the surface movement area is to be set as a risk control zone, with a safety distance around it, a safety fence and warning signs. Potential pollution risk is to be controlled from the solid waste attribute of the waste rock, tailings and heap leaching residue, with measures to control pollution of the surrounding soil and water: waste dumps, tailings reservoirs and heap leaching sites are to be provided with impervious measures according to the waste attribute and the site class so that leachate reaching the groundwater is reduced, following GB 18598 and GB 18599; where the stored waste is hazardous waste, closure is to include impervious measures following GB 18598; and where it is class II general industrial solid waste, closure is to include barrier measures following GB 18599. Soil erosion is to be controlled by integrated measures suited to the erosion features of the region, following GB 51018, GB/T 16453.3 and GB/T 16453.6.

9.3 Reclamation and restoration measures. Landform reshaping is to fix the layout and form of the reshaped landform from the hydrometeorological features, the regional relief, the micro-relief of the destroyed unit and the depth of the water table together with the reclamation direction and requirements, applying shaping and levelling works suited to local conditions, the reshaped landform preferably being close to the original; it is to be safe and stable, to favour the reclamation and restoration work and to agree with the surrounding landscape. Reshaping at the open pit, the waste dump, the tailings reservoir and the heap leaching site is to build on the artificial relief formed during production and to combine shaping and levelling with the geological environment treatment works and the pollution risk control works so that TD/T 1036 is met; areas of light damage such as in-situ leaching sites and pipelines are to keep the original relief; and where the bench slope of a waste dump or heap leaching site is higher than 10 m, slope cutting and benching is preferably applied. Soil reconstruction is to make full use of the stripped and stored topsoil, a borrow area used for nearby soil being itself reclaimed once borrowing ends, and no soil polluted above the limit by heavy metals or other toxic and harmful substances is to be used; reconstruction is to follow promptly on the formation of the permanent bench and platform of the open pit, waste dump, heap leaching site and tailings reservoir. Where hazardous waste or class II general industrial solid waste is stored, full soil covering is to be used, the thickness of the cover being set by the plant species and the damage they might do to the barrier layer; the cover thickness on a tailings dam is to be set by the plant species and the effect on dam safety; and after leaching at an in-situ leaching site ends, the injection holes are to be backfilled and sealed in good time, the backfilled surface having the same slope as the original ground.

9.3 (continued) For arable land and garden land, sites of serious or relatively serious potential pollution risk are preferably not reclaimed to those uses; full-area land preparation and soil covering is to be used, the cover meeting the requirements of TD/T 1036 for arable and garden land; the pollutant content of the cover soil is not to exceed the soil pollution risk screening values of GB 15618; and the reconstructed soil is to be assessed for cleanliness following HJ/T 166 and GB/T 33469. For forest and grassland, full-area preparation and covering is preferred where the soil source is sufficient; where it is not, pit or strip preparation and covering is preferred on platforms and tops and fish-scale pit or strip preparation on slopes, the soil quality meeting TD/T 1036; where there is no soil source, soil-free reclamation, reclamation with weathered rock and soil or tailings improvement may be used after feasibility trials; and the pollutant content of the cover soil of artificial pasture is not to exceed the screening values of GB 15618. Vegetation reconstruction prefers adaptable native tree and grass species, plants and pioneer plants tolerant of drought, poor soil and pollution following TD/T 1070.1, and local grasses that are easy to establish, fast growing, deep rooted, easy to propagate, stress resistant and low or stoloniferous; sites at risk of heavy metal pollution preferably take metal-accumulating or tolerant plants and sites at risk of acid water pollution acid-tolerant plants; the quality of seedlings and seed follows GB/T 15776. Species arrangement and planting take biodiversity protection as their aim and prefer the turf stripped and the species transplanted from the mine; the arrangement pattern is chosen among mixed tree and shrub, shrub and grass, tree and grass and tree, shrub and grass stands according to the climate, aspect, slope and surface material of the bioclimatic zone; in mines with better climate the pattern preferably forms a tree layer, a shrub layer, a herb layer, a litter layer and a soil layer that control surface runoff; afforestation follows GB/T 15776 and grassland establishment NY/T 1342. On high and steep slopes, vegetation is preferably established by hydroseeding, vegetation blankets or mats, concrete grids and eco-bags following GB/T 38360, and on high and steep open-pit slopes by planting climbers at the toe and hanging baskets on the face. Landscape construction takes biodiversity protection as its aim and builds the damaged water corridors, biodiversity corridors and landscape corridors of the mining area so that the reclaimed areas are connected to one another and to the local ecosystem; important sites may be given a cultural function drawing on mining culture; ponded pits and tailings ponds may be rebuilt as artificial wetland landscapes with a connected water system; areas of slight surface deformation and lightly damaged sites such as in-situ leaching workings, topsoil stockpiles and pipeline routes preferably recover the original landform; artificial hills formed by dumps, heap leaching sites and tailings reservoirs and the stepped relief of hillside open pits are preferably built into a mountain landscape in keeping with the surrounding scenery; and in desert, sandy and other water-short regions the open pit may be built into a rock landscape and the dumps, heap leaching sites and tailings reservoirs into a desert or sand landscape, with artificial measures against desertification, sand movement and the spread of sand. Ancillary works comprise irrigation and drainage, which are to build on the drainage system of the main mine works and be laid out for the reclamation direction once flood control and drainage needs are met, and roads, which preferably build on the roads of the main works and are to be planted along their length.

9.3 (continued) The provisions on landform reshaping, soil reconstruction and vegetation reconstruction of land in the stabilized damage zone follow TD/T 1070.1.

10 Management and maintenance, monitoring and evaluation, and adaptive management

10.1 Roads, irrigation, drainage, buildings and structures and other infrastructure are to be maintained regularly; where a facility is found not to be working properly or to be damaged, it is to be repaired or replaced in good time.

10.2 The period of land quality and vegetation tending is to be settled from the natural conditions of the mining area, the potential pollution risk of the site, the soil reconstruction and the vegetation reconstruction, and tending is to continue without interruption; for metal mines the subsequent tending period is generally three to five years, and for sites of high or relatively high potential pollution risk and for ecologically fragile areas six to ten years. According to the reclamation direction of the site, loosening, ploughing, fertilizing and biological and chemical improvement are to be applied at suitable times so that the environmental quality of the reconstructed soil is maintained and improved and the land can be used sustainably. Vegetation tending measures chiefly comprise fertilizing, irrigation, loosening, weeding, pest and disease control, supplementary planting and resowing, and follow GB/T 15776.

10.3 The key species and the biodiversity of the mining area are to be observed continuously and the ecosystem function assessed, the populations and the community composition and structure being optimized so that the restored ecosystem passes from formal recovery to functional recovery. With the reference ecosystem as target, the species and composition are to be maintained, biodiversity protected and the recovery of the plant community achieved, so that the productivity and self-maintenance of the ecosystem rise. Limiting factors for animal growth are to be removed, good animal habitat created and habitat connectivity restored so that animals return. Over the whole process of landform reshaping, soil reconstruction, vegetation reconstruction and landscape construction, the health management of the ecosystem is to be strengthened so that secondary degradation is avoided. The risks of flood, drought, insect attack and fire in the rebuilt ecosystem are to be lowered so that its relative stability is maintained and the sustainable use of land, water, biological and landscape resources and of the human settlement environment is safeguarded.

10.4 Monitoring and evaluation are to run through the whole of mine construction, production, closure and reclamation. Soil and water environmental quality data are preferably taken from the environmental impact report and its follow-up monitoring. Reclamation monitoring before, during and after extraction follows GB/T 43935. Adaptive management is likewise to run through the whole of construction, production, closure and reclamation, and is to include the assessment of mine geological environment stability, of soil quality against the standard, of the productivity level of the vegetation and of ecological resilience. On the basis of whole-cycle follow-up monitoring and evaluation, the effect of the mitigation and protection, preventive control and reclamation measures is to be assessed and newly arising ecological problems and latent ecological risks found in good time; and against the reclamation targets, the measures that might lead away from those targets or cause fresh damage are to be adjusted and corrected. Effectiveness assessment covers ecological effectiveness and socio-economic effectiveness and assesses the distance between the restored ecosystem and the reference ecosystem and the improvement of its function; it focuses on the reclaimed landform, soil, vegetation, landscape and biodiversity together with the satisfaction of public participation, and follows the relevant provisions of GB/T 43935.