A study was performed ata Heap Leach Copper Mining site in Chile to determine dry and saturated zones in order to improve the irrigation at the Heap Leach Copper Miningand increase the production of concentrate of Copper.
The surveys were performed on 25th of February 2015 in Chile with the AGI SuperSting WiFi R8 RES/IP instrument with 56 electrodes at 2m electrode spacing. Five parallel 2D resistivity surveys lines with 10m line spacing were performed.The Dipole-Dipolearray was used to collect the 2D electrical resistivity imaging data set and EarthImager software was used to model the data.
The dry and saturated zones were successfully mapped not only vertically but also laterally. The 3D inversion results showed successfully high resistive zones associated with poor irrigation as well low resistive zones associated with saturated zones at the Heap Leach Copper Mining Site.
05 September 2019
Altra Industrial Motion brands recently supplied braking systems and backstops for use on a variety of conveyors installed at a new open pit heap-leach gold mine in Siberia. When fully operational, the mine is expected to output an average of 230,000 ounces of gold annually.
30 August 2018
In many industrial environments the transmission of power through the drive train requires couplings that are able to carry high torque while also accommodating misalignment and vibration. Stromags range of Periflex Shaft Couplings use a highly flexible, rubber-fabric tyre element to transmit up to 15,000 Nm of torque, while compensating for radial, axial and angular misalignment. Further, wear is limited to the rubber element to minimise the burden of maintenance.
04 June 2018
A major manufacturer of dredging systems needed a reliable coupling solution with a small footprint for use on a new dredging vessel platform. The system features a 1200 HP diesel engine that drives a complex, custom-designed, eight-pad gearbox with primary output to a two-speed clutch that drives the systems main pump, as well as hydraulic pump pads to operate a crane and auxiliaries.
28 August 2017
18 April 2017
Altra Industrial Motion Corporation is offering a free Virtual Reality (VR) experience to all stand visitors at this years Hannover Messe. The mechanical power transmission specialist has launched the Altra Virtual Environments app for download to smartphones everyone who downloads the app prior to the show will be eligible to claim a free pair of VR glasses at the Altra stand.
For most of us portable means something you can put in your pocket or carry around easily. In mining our Super Portable concept refers to an 80 metre long modular conveyor unit that can move up to 10,000 tons of material per hour.
Extracting the various precious metals to make todays products involves processing large quantities of material to separate the commercial substances. Crushed ore is piled onto large pads that are sprayed with chemicals. The chemicals help break down and separate the precious metals from the waste material. The process, known as heap leach stacking, requires a big operational area and depends on large volumes of material to extract the metals in useful quantities.
Early heap leach systems used portable conveyors or grasshoppers progressively linked together and feeding a mobile radial stacker to build the pad from a fixed conveyor running alongside. Equipment was repurposed from the aggregate industry, but could not handle heavy-duty mining, running 24/7. Our early success came from offering more robust and reliable mining equipment.
Copper followed the trend in gold mining of using heap leaching techniques, allowing operators to develop mines to quickly process low-grade oxide ores for less capital investment. Copper mines were more numerous, but required higher tonnage rates to be feasible. In a heap leach pad, ore is stacked in strips or cells determined by the reach of the radial stacker and the number of portable conveyors extending from the overland conveyor to the far edge of the pad. As tonnage rates rose, the speed at which the equipment had to move and the rate at which new portable conveyors had to be removed from the main chain of conveyors on the pad increased.
To solve this problem, we developed new longer conveyors. The radial stacker grew in length from 36-40 metres to 64-70 metres. Portable conveyors grew from 38 metres to 76 metres, too big to be easily moved. The new designs had to be self-propelled and independently manoeuvrable so we developed and patented the Super Portable conveyor and stacking systems. The backbone of a Super Portable conveyor is its heavyduty truss structure, optimised for high structural weight efficiency. The ends of the central truss are mounted on crawler vehicles driven by electric motors / onboard diesel generators. With this system, Super Portable conveyors can climb and operate up to 10 degree grades.
The Super Portable concept created new potential for heap leaching. The 5,000 ton per hour barrier was broken with the first full system supplied to a large copper mine in Arizona running at up to 6,600 tons per hour. A system was installed in Chile and raised the bar again increasing the tonnage another 35%. With all 23 conveyors in operation, this system can stretch up to 1.8 kilometres across the pad and stack more than 130,000 tons per day.
We see potential for other applications beyond heap leaching. The units can be used for dry stack tailings, an emerging trend for reducing water use in mining. Dry stack tailings systems dewater the waste stream; the tailings are then conveyed and stacked rather than being pumping into a tailings pond. This method of depositing tailings mitigates the risk of dam failures. We installed the largest dry stack tailings system to date in Saudi Arabia, which has been operating successfully since 2011.
It is also possible to integrate overland conveyors and Super Portable conveyors to transport and stack waste rock or mix waste rock and filtered tailings to be deposited together, saving precious water, removing the risk of retaining dams and stabilising the waste/tailings pad. Major operators in copper, gold and oilsands are all looking at these concepts.
We are working with other equipment manufacturers and operators to use Super Portable conveyors with in-pit crushing and conveying (IPCC) systems. When faced with ever decreasing grades and higher strip ratios in hard rock mines, IPCC systems can use the highly mobile Super Portable conveyors to directly link a shovel and mobile crusher to high capacity overland conveyors extending out of the mine to reduce haulage costs.
Focusing the mine layout around conveyors instead of trucks is critical for effective IPCC solutions. IPCC systems are made to fit into existing mine plans, and lack the flexibility to adapt as the mine changes. The Super Portable conveyor, combining high mobility with high tonnage overland conveyors may be the next step in the evolution. We are developing systems for tonnages over 200% of todays typical production rates for open pit conveyors, using new megawatt class conveyor drive technologies.
The technical-economic indicator ofdump/heap leachingis the external manifestations ofdump/heap leaching technologystandard and economic effects. The reasons that influence the economic indicator are objective factors during dump/heaping leaching process, of which some factors will affect several technical-economic indicators simultaneously, for example, the ore properties not only influence the leaching yield, recovery rate, but also affect the consumption rate, moreover, its the crucial factor that determine the emission load of three wastes. Some technical-economic indicators are restricted by several factors simultaneously. For example, the leaching yield, is not only restricted by ore property, but also by the technical merit. Therefore, when choosing, determining and evaluating the technical-economic indicators, the factors that influence them shall be taken special consideration, and make conclusion after careful investigation and comparison.
Including the orebody occurrence, existing form, buried depth, ore reserves and the reserve level. They has great influence on the companys life, scale and cost. Therere many failures due to not clear about the geological condition of the deposit, and a large amount of investment was wasted.
Including the ores, composition, hardness, particle size, moisture content and etc, theyre main factors that influence the leaching yield, electricity and water consumption, and the effluent volume. Whats more, theyre main factors affecting the aggregate investment.
The local natural factors such as temperature, wind strength, terrain, river, rainfall and etc, will influence the determination of technological parameters, also affect the quantity and model selection of the equipment, theyll lead to change of the aggregate investment and production cost.
All that time it took to design and build postponed your ability to generate income. What if we told you we've got a library of pre-engineered plants ready to build, rapidly install and produce profit?
Superior replacement crusher parts are taken from the same warehouse used for our manufacturing operations. That means you get an equal part, with equal quality, thats designed exactly for your machine.
Heap leach mining operations continually seek greater capacity, continuous material flow, and reduced downtime. In any precious metal application including gold, copper and ore these challenges are ongoing top-of-the-mind initiatives, particularly due to the complexity of stacking plans. Material handling equipment must be highly mobile and extremely flexible. And, for optimum performance, more and more operations are utilizing integrated conveyor systems, which can be custom-engineered for the specific pad design. The speedy payback from the latter is measured in more tons per move, larger leach pad footprints and increased profitability.Because every heap leaching operation maintains a specific process with unique characteristics, mines are far more likely to improve efficiency with a customized and comprehensive material handling system, says Jarrod Felton, president of Superior Industries, a manufacturer of aggregate- and mine-duty conveyors, components, and integrated systems customized for small-to-large heap leach operations; and suitable for valley fill pads, billiard table pads, and advance or retreat stacking.Felton says that an integrated heap leach system is comprised of a core group of mine-duty conveyors, with the customization of the system being applied with various belt lengths and widths, belt speeds, and load areas; as well as choices in hoppers, mobile tracks, control systems, electrical components, and the total number of jump or grasshopper conveyors. This strategically selected system of machines and machine attributes ensures smooth material transfer and far greater efficiency over that of older, conventional methods.Felton explains that currently, many heap leach mining operations work in a manual radial stacking mode. Operators will move the radial stacker with a loader to a given location, leaving it to stack there while they perform other maintenance duties. Later the operators return to either fill in holes or move the stacker to the next location. This typically results in saw-tooth pile tops, which are not ideal for irrigation, he says.
Superiors heap leach system is comprised of a core group of mine-duty conveyors, with the customization of the system being applied with various belt lengths and widths, belt speeds, and load areas; as well as choices in hoppers, mobile tracks, control systems, electrical components, and the total number of jump or grasshopper conveyors.
Alternatively, automated heap leach conveying systems are programmed to stack per desired lift specifications. At the core of the system is the mine-duty TeleStacker Conveyor, which is engineered with an internal stinger conveyor that maintains constant motion along a cell, distributing material evenly to achieve a flat top to each heaped pile, while also piling more material per move. Its longer stinger conveyor, over that of conventional radial telescoping units, allows for greater flexibility in complex valley fill applications, says Felton.
He explains that the conveyor is equipped with the FD Series Axle assembly, a technology that allows a quick transition from radial to linear mode, enabling movement along the leach pad cell centerline. Also, the unit features the patented FB Undercarriage support system, which is constructed of durable steel and a tubular braced structure that prevents any twisting and shifting. This level of stability is required for the uneven ground and the constant movement typically seen in the heap leach environment, he stresses.
As to additional mobility options, Felton says that operations may utilize radial travel tracks and/or a track-mounted mobile pivot base in conjunction with the telescoping conveyor. Radial travel tracks are a cost-effective method to gaining optimum flotation and traction. When combined with the mobile pivot base, operations can achieve free-ranging onsite and transfer point mobility as well as radial travel capability all while reducing the need for multiple trucks and loaders, he says.
Integrated with the telescoping radial stacker is the Horizontal Index Conveyor (HIC), a fully-skirted unit with a frame that mounts to the stacker. For greater heap leach site mobility, the track drive on the unit is designed to move itself and the radial stacker along the cell centerline and for maximum flexibility, the HIC can be fed at any point along the length of the conveyor, says Felton. He adds that when combined with portable jump or grasshopper conveyors, the HIC minimizes the frequent removal or adjustments of the jump conveyors along the material transfer line. Ultimately, the combined mobility and flexibility of the HIC is key to building larger leach pad footprints, he says.
Next, Felton explains that a horizontal feed conveyor runs perpendicular to both the HIC and the grasshopper conveyors. It transfers material from the grasshopper conveyor to the HIC to maintain a consistent, steady material flow, he says.
Built in standard lengths of 100 feet or engineered in custom lengths, multiple grasshopper conveyors comprise a substantial length and are combined consecutively to transfer material to the stacking conveyors. Felton says that retreat stacking will move in increments of the grasshopper conveyor length by removing one at a time, while advance stacking requires the insertion of a jump conveyor upon moving forward. For very large systems, there are super portable grasshopper conveyors that range from 215- to 250-feet in length.
Operations can also utilize a tugger, which is a self-contained and tracked mobile pivot base, to move grasshopper conveyors into place. It can also be used as a single point axle on a horizontal feed conveyor, says Felton. He also notes that the companys new Trailblazer Portable Groundline Conveyor can be used to replace some the grasshopper conveyors. This gives the system the advantage of fewer transfer points and electrical connections, and lesser move frequency, he adds.
While a total systems approach to heap leach conveying may seem an unwieldy proposition to some operations, Felton stresses that adaptability is made easier when the systems provider also takes a total approach to the design/build factor. Today its common for manufacturers to sub-contract to others for both large and small components. At Superior, we manufacture all our components and conveyors, and engineer our systems as a whole to ensure such things as smooth material movement at all transfer points as well as the necessary electrical integrity required for the integration of multiple conveyors, for example. Our approach also allows greater control over lead times and delivery, he says.
From system installation through startup, Felton says that his team provides onsite assembly and training. This ensures safe operation and allows the crew to experience productivity right from the start.
Lastly, Felton points to the fact that Superior Industries was founded and built on the premise of making conveyors mobile, and minimizing the need for costly loader, dozer and haul truck use. So it is no surprise that we are drawn to the heap leach mining market as it has one of the highest requirements for mobility, he says.
An index-organized table has a storage organization that is a variant of a primary B-tree. Unlike an ordinary (heap-organized) table whose data is stored as an unordered collection (heap), data for an index-organized table is stored in a B-tree index structure in a primary key sorted manner. Besides storing the primary key column values of an index-organized table row, each index entry in the B-tree stores the nonkey column values as well
.,SQL.I/O.:1..:create index on ():create index ind_ename on emp(ename)2...,.:create unique index on ():create unique index ind_name on emp(ename)3.,.:select .... from table where ...and ... :create index ind_name on emp(ename,sal)4...: 1001 10011002 20011003 30011004 4001?,.:create index ind_empno on emp(empno) reverse5..,,.,.:create bitmap index in_deptno on emp(deptno)6..,oracle,.:create index ind_sal on emp(lower(ename)) ,,query rewaite .7..,.,,,.,,I/O..:create table ind_table(id number primary key,name varchar2(20))organization index;OK,.,Oracle.,.:(1),,Oracle.::create table order_mast(order_id number(4),order_name varchar2(20))partition by range(order_id)(partition p1 values less than(1000),partition p2 values less than(2000),partition p3 values less than(maxvalue));:create index myindex on order_mast(order_id) local(2)...:create index glb_ind on order_mast(order_id) globalpartition by range(order_id)(partition p1 values less than(1500),partition p2 values less than(maxvalue));(3),,..
1. Create table test( Id int, Name varchar2(10) ); UPDATEINSERT SELECT create table t( a int, b varchar2(4000) default rpad('*', 4000, '*'), c varchar2(3000) default rpad('*', 3000,'*'));insert into t(a) values (1);insert into t(a) values (2);insert into t(a) values (3);delete from t where a=2;insert into t(a) values (4);SQL> select a from t; A---------- 1 4 3
2. (index organized table, IOT) a. b.IOT.c.IOT IOTI/O between create table indexTable(ID varchar2 (10),NAME varchar2 (20),constraint pk_id primary key (ID) ) organization index;3. index cluster ORACLE BLOCK create cluster emp_dept_cluster( deptno number(2) )size 1024/
size create index emp_dept_cluster_idxon cluster emp_dept_cluster/ create table dept( deptno number(2) primary key, dname varchar2(14), loc varchar2(13))cluster emp_dept_cluster(deptno)/
create table emp( empno number primary key,ename varchar2(10),job varchar2(9),mgr number,hiredate date,sal number,comm number,deptno number(2) constraint emp_fk references dept(deptno)) cluster emp_dept_cluster(deptno) /
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Index-Organized Table, IOTIOTIOTIOTIOTIOTROWIDIOTOracleROWIDROWIDIOTIOTiot
iotblocksOLAP12345betweenandiotoracleAn index-organized table has a storage organization that is a variant of a primary B-tree. Unlike an ordinary (heap-organized) table whose data is stored as an unordered collection (heap), data for an index-organized table is stored in a B-tree index structure in a primary key sorted manner. Besides storing the primary key column values of an index-organized table row, each index entry in the B-tree stores the nonkey column values as well B(), B
Altertablet88initrans2overflowinitrans4;--initransC:\>sqlplusSQL*Plus: Release 22.214.171.124.0 - Production on 5 19 11:09:06 2005Copyright (c) 1982, 2002, Oracle Corporation.All rights reserved.:wwf/wwf:Oracle9i Enterprise Edition Release 126.96.36.199.0 - ProductionWith the Partitioning, OLAP and Oracle Data Mining optionsJServer Release 188.8.131.52.0 - Productioncreate table heap_stocks( symbol varchar2(4),ticker_dt date,price number,constraint heap_stocks_pk primary key (symbol,ticker_dt));create table iot_stocks( symbol varchar2(4),ticker_dt date,price number,constraint iot_stocks_pk primary key (symbol,ticker_dt))organization index compress 1;10002001 SQL> set timing onSQL> begin2 for i in 1..200 loop3 insert into heap_stocks4 select to_char(rownum, 'fm0009'), trunc(sysdate)+i, rownum5 from all_objects where rownum <= 1000;6 end loop;7 commit;8end;9/PL/SQL :00: 00: 18.06SQL> set timing onSQL> begin2 for i in 1..200 loop3 insert into iot_stocks4 select to_char(rownum, 'fm0009'), trunc(sysdate)+i, rownum5 from all_objects where rownum <= 1000;6 end loop;7 commit;8end9;10/PL/SQL :00: 00: 31.072018IOT31IOT2. SQL> conn:sys / nolog as sysdbaSQL> shutdown immediateORACLE SQL> startupORACLE Total System Global Area135338868 bytesFixed Size 453492 bytesVariable Size 109051904 bytesDatabase Buffers 25165824 bytesRedo Buffers 667648 bytesSQL> exitOracle9i Enterprise Edition Release 184.108.40.206.0 - ProductionWith the Partitioning, OLAP and Oracle Data Mining optionsJServer Release 220.127.116.11.0 - ProductionSQL> conn:wwf/wwfa.autotraceSQL> set autotrace traceonlySQL> set timing onSQL> set autotrace traceonlySQL> select * from heap_stocks where symbol = '0001';200:00: 00: 00.08Execution Plan---------------------------------------------------------- 0 SELECT STATEMENT Optimizer=CHOOSE 1 0 TABLE ACCESS (BY INDEX ROWID) OF 'HEAP_STOCKS' 2 1 INDEX (RANGE SCAN) OF 'HEAP_STOCKS_PK' (UNIQUE)Statistics---------------------------------------------------------- 239recursive calls 0db block gets 259consistent gets 207physical reads 0redo size 5706bytes sent via SQL*Net to client 646bytes received via SQL*Net from client 15SQL*Net roundtrips to/from client 4sorts (memory) 0sorts (disk) 200rows processedSQL> select * from iot_stocks where symbol = '0001';200:00: 00: 00.02Execution Plan---------------------------------------------------------- 0 SELECT STATEMENT Optimizer=CHOOSE (Cost=2 Card=82 Bytes=2132) 1 0 INDEX (RANGE SCAN) OF 'IOT_STOCK_PK' (UNIQUE) (Cost=2 Card=82 Bytes=2132)Statistics---------------------------------------------------------- 299recursive calls 0db block gets 63consistent gets 4physical reads 0redo size 5706bytes sent via SQL*Net to client 646bytes received via SQL*Net from client 15SQL*Net roundtrips to/from client 6sorts (memory) 0sorts (disk) 200rows processed25963IOTb sql_trace:SQL> conn:wwf/wwfSQL> alter session set sql_trace = true;SQL> select avg(price) from heap_stocks where symbol = '0001';AVG(PRICE)---------- 1SQL> select avg(price) from iot_stocks where symbol = '0001';AVG(PRICE)---------- 1SQL> alter session set sql_trace = false;tkprofselect avg(price) from heap_stocks where symbol = '0001'call count cpu elapsed disk query current rows------- -------------- ---------- ---------- ---------- --------------------Parse 1 0.31 0.33 1 1 0 0Execute 1 0.00 0.00 0 0 0 0Fetch 2 0.00 0.39 203 208 0 1------- -------------- ---------- ---------- ---------- --------------------total 4 0.31 0.73 204 209 0 1Misses in library cache during parse: 1Optimizer goal: CHOOSEParsing user id: 61Rows Row Source Operation---------------------------------------------------------- 1SORT AGGREGATE 200 TABLE ACCESS BY INDEX ROWID HEAP_STOCKS 200 INDEX RANGE SCAN HEAP_STOCKS_PK (object id 30391)select avg(price) from iot_stocks where symbol = '0001'call count cpu elapsed disk query current rows------- -------------- ---------- ---------- ---------- --------------------Parse 1 0.02 0.03 0 0 0 0Execute 1 0.00 0.01 0 0 0 0Fetch 2 0.00 0.07 3 4 0 1------- -------------- ---------- ---------- ---------- --------------------total 4 0.02 0.11 3 4 0 1Misses in library cache during parse: 1Optimizer goal: CHOOSEParsing user id: 61Rows Row Source Operation---------------------------------------------------------- 1SORT AGGREGATE 200 INDEX RANGE SCAN IOT_STOCK_PK (object id 30393)TomSo, we did 203 physical IO's to process the HEAP table.What that tells me isthat our data for stock symbol 0001 is spread out on 200 blocks (200 days, 200blocks).In order to cache the results for this query, we need 200 blockbuffers.We needed to do that IO to get the answer initially.Now, looking at the IOT we did 3 physical IO's -- we cached 3 blocks -- and gotthe same answer!Not only that but by using index key compression I was able toremove he redudant 0001's from the data -- we can cache this much moreefficiently and getting it the first time takes seriously less IO.Very nice.3 SQL> set autotrace offSQL> delete from heap_stocks;200000:00: 00: 26.02SQL> delete from iot_stocks;200000:00: 00: 08.0826IOT8!
Although a normal index does not storenull key values, cluster indexes store null keys. There is only one entry foreach key value in the cluster index. Therefore, a cluster index is likely to besmaller than a normal index on the same set of key values.
clusterblocknullkeynull keynullkey?clusterb-tree indexnullkeysoracleisnullnullnullnull
CREATE CLUSTER hash_cluster(hash_key NUMBER)HASHKEYS 1000SIZE 8192;HASHKEYOracleHASHKEY*SIZEHASHKEYS/TRUNC(BLOCKSIZE/SIZE)I/OCPUCPUI/O1. 2.DMLHASHKEY3.HASHKEY
This new and innovative SQ1863EE is the first of many MAX Plants manufactured in our Australian facility. The SQ1863EE electric sizing screen belongs to the ETRAC range of machines. ETRAC is a hybrid electric crushing and screening range reducing carbon footprint and running costs for the client.
Having the options of fixed, modular, portable, or mobile equipment gives you endless opportunities. We provide you with versatile mineral processing, crushing and screening plants that can be re-configured to any application and suit multiple layout options.
The use of geosynthetics in mining operations grows annually, as mining companies focus on the technical and economic advantages of geosynthetics. These materials have enabled more efficient barriers, stronger access roads, space-saving and safety-enhancing retaining structures, and much more. Kent von Maubeuge and Raquel Ribera summarizing the use geosynthetics in mining. This publication is part of Geosyntheticas GeoAmericas series. FEATURE IMAGE: NAUE.
The daily mining rates, scale of single-site operations, and costs associated with mining increase every year. Advances in extraction technologies have greatly increased recovery rates from ore bodies. Mine designs previously thought to be too big to be possible are achieved every year or two so that an average mine today is significantly larger than an average mine just 10 years ago (Smith, M.E., 2013).
To construct on this scale, which is often necessitated by marketplace price points and competition for investor support, requires substantial engineering to make mines economically feasible and environmentally sound.
The heap leach projects are some of the largest users of geomembranes, by some estimates consuming 40% of all geomembrane produced, and continued uses are still being developed (Christie, M.A. 2013). Heap leaching has grown substantially as a technique for extracting valuable material from ore. Ore heaps of 200 m are being constructed.
Mountaintop and valley leach designs are implemented. Geosynthetic lining systems contain the pregnant solution so that it is not lost in seepage into soils and does not flow into local waterways. Gold, copper, nickel, uranium, and even rare earths are being heap leached. Geosynthetics contain the valuable reserves and isolate the waste (e.g. the tailings), thus providing economic and environmental advantages to the site.
Raincoat liners keep storm water out of ore heaps so that the pregnant solution is not diluted. Processing is more efficient this way. Also, geosynthetic lining systems protect water resources on site. With water costs in some regions having increased by 300% in the past five years, conserving water on remote mining operations significantly reduces expenses (Smith, M.E., 2013).
Containment isnt the only solution needed to keep mining operations competitive and viable. A vast range of geotechnical works are required for operational performance and environmental security. Geogrid reinforcement stabilizes berms, embankments, crusher walls, and other soil structures. They support access roads so that 100 ton payloads can pass daily for years on site without costly roadway failures. (A mine can lose millions of dollars, USD, per day if an access road fails.)
Geotextiles provide separation of granular layers, filter stability in geotechnical constructions, and protection of other geosynthetics. In combination, these materials improve the recovery of valuable materials, isolate contaminated waste, keep sites open, and make closure a more efficient and less costly endeavor.
Geosynthetic solutions for the mining industry are engineered for long-term performance in all environments and with the chemical compatibility necessary to meet the economic and environmental goals of todays mining operations. Solutions include:
Without question, heap leach has become an enormous driver to the growth of mining operations around the world. Twenty-five years ago, only about 3% of copper and gold supplies were produced through heap leaching. Today, the volume is surpassing 30% annually (Smith, M.E., 2013). Valuable chalcopyrite copper, previously not considered economical in heap leach development, is now heap leached, as is nickel laterite, uranium, and even rare earths.
The growth of heap leaching is heavily tied to the massive scale on which mines are being built, with as much as USD $2 billion being invested in single sites. Heap leach stacks can near 200 m as operations look to more quickly prove site yield.
Heap leaching accomplishes thisbut only with the containment support of geosynthetics. Geomembranes and geosynthetic clay liners (GCLs) are used in lining system solutions as heap leach pad liners, pregnant solution trench liners, processing pits, onsite water storage, raincoat covers over ore stacks to shed storm water (rather than dilute the leach heap solution), and onsite wastewater management.
Geosynthetic lining solutions enable steep slope (including mountaintop) developments. Pregnant solution flows more easily from heaped ore, and valuable material is not lost in seepage into soils or local waters. Onsite water is managed more efficiently, which also improves site costs, as water and wastewater management is a major cost in mining.
High-density polyethylene (HDPE) geomembranes feature exceptional chemical, stress crack, and UV resistance. They have the durability and chemical compatibility to withstand aggressive mining heap leach solutions in stacks and solution trenches. Available texturing can enhance the frictional characteristics necessary for lining system slope stability. And for onsite water management and processing fluid containment, geomembranes are an economical and efficient solution.
Geomembranes are not all that mining sites require. Nonwoven geotextiles provide long-term, robust protection of and frictional stability for geomembranes on difficult terrain and in tall ore stack scenarios. Additionally, composite lining solutions (geomembranes with geosynthetic clay liners, GCLs) provide dependable, efficient, long-term lining performance for improved heap leach economics and environmental performance if used in a mining operation.
When an ores valuable deposit is extracted, what remains of the ore is waste. Often, it is a high percentage of the ore handled at the mine. Potentially contaminated from the extraction process or containing environmentally harmful components, tailings must be isolated to prevent long-term environmental damage.
Design engineers working on mines must allot significant space for proper containment of tailings. All or much of this area must be sealed with an impermeable geosynthetic (e.g., geomembrane) or composite lining system (e.g., geomembrane/geosynthetic clay liner). These sealing systems might protect the base and walls of an impoundment. Often, the surface of the tailings will be covered by a geosynthetic system after cell or mine closure.
As mine sites increase in size, the engineering needed to properly contain the volume of tailings has intensified. This scaling up of containment frequently requires not just lining systems but reinforcement and sealing systems for perimeter berms on tailings pond. Weaker, earthen-only berms are at risk of saturation, erosion, and failure. Furthermore, the increasing depth of tailings storage ponds requires stronger containment engineering design. The geosynthetics used must be durable and proven in aggressive environments over the long term. The depth of a tailings pond might exceed 50 m, for example. In these cases, the contaminated, generally sludgy waste is too deep and hazardous for the lining and reinforcement system to be monitored. With the environmental security of the site relying on these environmental protection systems, the geosynthetics selected must be trusted.
Evaporation is used in a variety of mining operations to separate valuable materials from water or brines. Diverse salts, for example, can be extracted by evaporation. Lithium-rich brines may be concentrated through evaporation. These materials, when harvested from solar ponds, are then able to be refined into items used across a wide variety of industries, in agriculture, in food products, etc.
Geosynthetic lining solutions are used to prevent the loss of valuable materials in seepage. They also provide strong environmental protection. The potentially aggressive nature of the material being mined by evaporation demands environmental care, especially with the concentrated masses that the evaporation process yields.
In many situations, pregnant solutions are pumped into the engineered pond for multiple cycles until the pond has been filled with a sizable enough harvest to economically justify collecting it. The system will likely be exposed to both the material of interest and difficult environmental conditions for a considerable period of time (e.g., years). As such, long-term performance and durability are essential for an evaporation pond lining system.
The life of a mine varies wildly. It could be shuttered after 6 months due to a swift decline in market prices for metals. That same site might be reopened 10 years later when a rise in prices makes the site economically viable again. A mine might operate for 20 years with little interruption. It might even change the type of ore it concentrates on multiple times over those 20 years. Ownership of the site can transfer. The development of new extraction technologies might cause some long-closed facilities to be reopened so that ore can be further exploited.
Whatever occurs during the active phase of a mines life, the need for responsible closure is always present. Mining activities involve significant disturbance of soils. Dangerous chemicals are used. Environmental threats will remain after operations cease.
One of the most effective ways to improve the long-term safety of the site is to isolate what had been the mining zones (e.g., former heap leach or tailings storage facility) by installing a geosynthetic capping system.
Geomembranes, geosynthetic clay liners, geotextiles, and geocomposite drainage materials are used to cover, encapsulate, and cleanly isolate contaminated soils. These systems eliminate infiltration of precipitation, prevent polluted runoff, allow clean soil to be installed on top to support healthy vegetation re-establishment, and much more.
Access roads are especially integral to a mines viability. Ore must move around and away from the site. Shipments of supplies must not be impaired. Site access delays of a single day can cost millions of dollars (USD). Extended interruption in access to the site can threaten the mines continued operation, as investors and mine owners might no longer consider it economically viable (Smith, M.E., 2013).
The massive vehicles used in mining today require extremely strong roads. Haulers carry payloads of more than 100 tons. For ore, oil sands, rock, and coal operations, the roads must sustain repeated passes of these vehicles over years of mine activities.
Geogrid reinforcement materials and separation geotextiles are used to redistribute the tensile forces within the road and prevent the mixing of fines and coarse aggregate. The increased road strength mitigates the risk of road erosion and rutting in wet or arid mining environments.
These same reinforcement, separation, and drainage control materials are used in various other geotechnical applications in mining. The difficult terrain that characterizes many sites requires a number of vertical or near vertical constructions to be built, such as to support crusher walls. Mechanically stabilized earth (MSE) walls, reinforced with geosynthetics, are a common and effective strategy. Also, there are embankments, abutments, operating pads beneath heavy equipment and cranes, and many other points at which soils must be reinforced to enable the little city that a mine is to function as designed.
In mining applications, such as heap leach facilities, evaporation ponds or tailings impoundments, where typically very high loads occur, geomembranes are more commonly used. Typical raw materials for geomembranes are: Linear Low Density Polyethylene (LLDPE), High Density Polyethylene (HDPE), Polyvinyl Chloride (PVC), Polypropylene (PP) and Ethylene Propylene Diene Terpolymer (EPDM). However, due to their high chemical resistance and physical properties mainly HDPE geomembranes are used. Additionally to the geomembrane properties other design issues must be taken into account, such as the effect of high stresses, the type of foundation and placed material under and on top of the geomembrane.
The foundation conditions should be firm to minimize settlements during the service life of the facility. Otherwise stress and over-elongation of the geomembrane could occur, resulting into damage of the geomembrane. Subgrade surfaces should provide a smooth, flat, firm, unyielding foundation for the geomembrane with no sudden, sharp or abrupt changes or break in grade that can tear or damage the geomembrane and additionally be free of loose rock fragments (>10 mm or 0.4 inches), sticks, sharp objects, or debris of any kind. Protection nonwovens can be used to protect against puncturing from soils.
The liner systems shown in Figure 1 to 3 can be either a single geomembrane, a composite lining system with a GCL or a double lining system with a geosynthetic drainage mat in between as a leak detection system. In many countries, landfills are first regulated by federal agencies through a rulemaking process. Typically, in the US geomembranes are made of HDPE and have a thickness of 1.5mm (60mils) in thickness and follow the GRI-GM13 specification. However, other countries have higher requirements, e.g. Germany requires an HDPE geomembrane for landfills with a thickness of 2.5mm (100mils).
In the mining industry there are no specific regulations for barrier applications, so that the liner thickness is generally selected based on experience, anticipating ore loads, the grain size of the material placed on top of the geomembrane and the material underneath. Due to the typical required chemical resistance required for the geomembrane HDPE is used in most cases. HDPE should be used where:
Geosynthetic clay barriers (GBR-C): Factory-assembled structure of geosynthetic materials in the form of a sheet in which the barrier function is fulfilled by clay. [Current ASTM terminology discussed definition similar to ISO 10318]
Geosynthetic clay liners (GCL): Factory-assembled geosynthetic barrier consisting of clay supported by geotextiles that are held together by needling, stitching, or a chemical adhesive. [Current ASTM terminology discussed definition]
Multi component Clay geosynthetic barrier (MGCL): A Clay or Geosynthetic Clay Liner (GCL) with an attached bituminous, polymeric or metallic barrier decreasing the hydraulic conductivity or protecting the clay core, or both. [Current ASTM terminology discussed definition]
GBR-Cs are used in mining applications, such as heap leach facilities, evaporation ponds or tailings impoundments, process solution containment, storm water containment, wastewater treatment ponds, closures and reclamation.
Harsh environmental conditions challenge the engineers designing these types of projects. In some applications the lining system can request a composite lining system with a geomembrane or a multi-component GCL. Due to the benefits GCL provide, they are more and more seen as an alternative to compacted clay liners in mining applications and in some cases an MGCL can be an alternative to a geomembrane. Some GCL benefits are:
However, the designer should consider site specific conditions (soil material, slope angle, interface friction) and specify relevant characteristics to ensure a long-term and safe design. Current standard GCL properties could be on the lower limit (e.g. GRI-GCL-3), so that increasing some GCL properties (e.g. mass per unit area of the geotextile and bentonite component) are in some cases recommended.
The Geosynthetic Research Institute has published a White paper # 5 (GSI 2005b) and a GRI-GCL3 (GSI 2005) standard and has made aware the necessity to consider several important topics, especially overlap separation under certain conditions of pre-hydrated GCLs. However, this topic can be solved by means of immediate soil coverage or an increasing overlap for these types of products.
An interesting alternative for mining applications are multicomponent GCLs. By adding an extruded polymer coating to the needle-punched GCL this product type is suitable to more mining applications, especially in presence of aggressive liquids which might influence the performance of the bentonite, especially if not hydrated.
Further advantages of extruded polymer coated barriers are: Prevention of Root Penetration; Increasing Resistance against Desiccation; Bentonite Piping Resistance under High Water Gradients; Lower Permeability; Barrier against Ion Exchange; and Gas Barrier.
To ensure the long-term performance of extruded polymer coated GCLs other design issues might be of concern and should be considered prior to the installation: Durability of the Coating; Resistance against Installation Stress; Overlapping of Polymer Coated GCLs; Transmissivity between coating and GCL; Interface and internal Shear; Peel Value of Coating.
As a separation layer, geotextiles are used to prevent adjacent soil layers or fill materials from intermixing. In filtration applications, nonwoven geotextiles are used to retain soil particles while allowing the passage of liquids through the filter media.
Needle-punched (mechanically bonded) nonwovens are robust geotextiles capable of withstanding harsh installation conditions and challenging construction loads. Their unique flexibility and elongation properties combine to provide high puncture resistance without sacrificing frictional of filtration properties. When properly selected, needle-punched nonwovens can provide superior long-term filtration and achieve high interface friction angles.
The aim of testing the protection behavior of a nonwoven geotextile for a geomembranes is to help ensure long-term, effective protection. To simulate site conditions the mechanical protection is examined using a modified long-term plate-loading test (EN 13719).
An elastomer disk with a Shore A hardness of 45 50 is installed as the base layer in a cylinder with a diameter of 30 50 cm. A soft metal sheet is placed on this, followed by the geomembrane and the protection layer, and finally by the site material which is supposed to be laid on top. The calculated load is then applied by a pressure foot and regulated using a load cell device underneath the elastomer disk.
The deformations of the geomembrane are visible as permanent deformations in the soft metal sheet. After the specified loading period the metal sheet is removed and the indentations/deformations are measured.
In nearly all protection layer systems, deformations occur in the geomembrane which need to be quantitatively assessed by reference to the indentations in the soft metal sheet. This also applies to the joints and at overlaps.
According to various publications protection layers are suitable if the indentations conserved in the soft metal sheet after the mechanical protection efficiency test with a particular applied load show bulge elongations less than 0.25 % and no damage has occurred which might have an adverse effect on the functionality.
Due to the expected service life (>>100 years) of a geomembrane, for landfill base lining system requirements request often a maximum deformation of 0.25%. In mining applications a shorter service life may occur, so that higher deformations, however lower than 1.5%, may be acceptable. A critical aspect for determining the long-term performance is also the temperature of the liquid over the geomembrane.
Drainage in heap leach pads is important to metal recovery, stability, and leakage control. Regardless what type of drainage material is selected (aggregate or geosynthetic) the liquid drainage layer at the base of heap leach pads should fulfill the following requirements:
While most heap leach pads are covered with aggregate as drainage material (typical more than 0.5m crushed gravel (10 mm to 50 mm) geosynthetic drainage layers are now more and more used as an alternative to the conventional gravel drainage system.
A geosynthetic drainage system is defined as: Three-dimensional prefabricated product manufactured from synthetic raw materials, consisting of a drainage layer (core) which is in most cases covered with at least one geotextile filter, for liquid and/or vapor transportation.
In order for a geosynthetic drainage system to perform equivalently to a mineral drainage layer in e.g. heap leach pads or to out-perform it, performance tests must be sufficient to demonstrate its long-term performance. These should include the filter performance of the geotextile filter, the long-term compression behavior of the geosynthetic drainage system under the site loads, the long-term horizontal (in-plane flow/transmissivity), as well as other site specific requirements, such as interface shear behavior or puncture resistance.
The design engineer typically will have the option between a mineral drainage layer and a geosynthetic drainage system during the evaluation and selection process. Engineers are more familiar to mineral materials and oversee the potential in geosynthetic drainage systems. However, it is often overseen what disadvantages can occur by using a mineral drainage layer. Placing this type of material directly on top of a geomembrane causes puncture stresses and can damage the geomembrane already during the placement process. Fur stresses occur during the loading of the heap leach pad, especially if no protection layer or an insufficient protection layer is used. The placement of the mineral drainage layer is also time consuming and can slow down the entire mining operation. Geosynthetic drainage systems on the other hand offer many advantages. Ease of installation, especially on the slopes, consistency in material properties, quicker installation, combined puncture protection and drainage layer, and in many cases cost savings.
In mining, geogrid applications include base course reinforcement and stabilization, reinforcement of slopes and retaining walls, and reinforcement of tailings ponds cover layers. Where the bearing capacity of soils is insufficient or shear characteristics too low to be stable for planned slope inclination or loadings, the geogrid reinforcement helps to bridge the gap to reach sufficient stability and safety.
The geogrid structure should provide stiff apertures. This influences the ability for lateral confinement of the aggregate which interlocks in the apertures. The greater the aperture stability of the geogrid the better is the lateral restraint provided for the granular material. The interaction with the aggregate is one of the main principles for geogrid reinforcement. As a result of the interlocking mechanism the geogrid absorbs stresses from the soil and increases safety and serviceability.
For optimal absorption of the stresses the geogrid needs to provide high strength at low strain. The greater the tensile modulus at low strain, the lower the resulting strain and finally deformation in the structure. The ultimate tensile strength is affecting the level of available tensile strength at low strain as well as the increase in ultimate strength results in the same rate of increase at low strain.
In structures where the geogrid is utilized to provide sufficient stability and safety as determined by a structural analysis, the long-term behavior of the product becomes decisive. Different raw materials and manufacturing processes influence characteristics like creep behavior, robustness against installation damage, and chemical/biological influences. Those values directly influence the long-term design strength of a product which is considered in the stability analysis. Products with equivalent ultimate strength will usually differ in their resulting long-term design strength.
In order to ensure a safe and reliable stability analysis, dimensioning and design, it is important to have detailed information on each single shear plane. Safety is therefore top priority for all applications, especially on slopes. Geomembranes are therefore available with smooth or structured surfaces.
However, it is necessary that a project specific analysis should be performed, including direct shear testing, to confirm slope stability calculations. In cases where slope stability is not ensured with an accepted safety factor, geogrids can be used to improve the stability of soil veneers or entire lining systems.
Climate conditions might also be important to consider, especially if exposed for a longer period. Higher elevations can increase heating by solar radiation, exposure to UV but also temperature changes. Additionally construction considerations can include:
This paper presents an overview about common heap leach pad liner systems and their design requirements. Especially the geosynthetic components, the geomembrane and, if used, the geosynthetic clay liner have to be chosen in consideration of the harsh conditions of a heap leach pad. Therewith the requirement of well-designed and qualitative geosynthetic components comes up which achieve their function over a sufficient period of time.
Geosynthetic materials have been proven effective on various mining applications. Manufacturers do offer support for designers in questions of applicability and product choice of any geosynthetic material with respect to the project specific boundary conditions.
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Depending upon the method of measurement, the angle of repose value varies appreciably.The selection of an appropriate method of measurement should be based on the field of application.The size and shape of grains that comprise a granular pile affect its angle of repose considerably.The angle of repose of a particular material is not necessarily equal to its angle of internal friction.There is a vast range of application fields where the use of angle of repose is applicable.
The abundance of granular materials and powders that are being used in several fields, along with their broad applications, requires a comprehensive understanding of both their macro- and micro-mechanical behavior. The fabric and structural properties, or the inter-particle properties, such as the angle of repose, do affect the behavior of granular materials. This comprehensive review indicates that the angle of repose of granular material is an essential parameter to understand the micro-behavior of the granular material and, then, to relate it with the macro-behavior. Therefore, this extensive review was prepared about the repose angle theory, its definitions, method of measurements, appropriate applications and the influencing factors.
Description: The static (a) and dynamic (b) angles of repose are inherent parameters for powders and depend on the items shown in Venn diagram.Download : Download high-res image (39KB)Download : Download full-size image
Hamzah M. Beakawi Al-Hashemi is a Civil (Geotechnical) Engineer. In 2012, he gained his BSc. degree from the University of Khartoum in Sudan. Hamzah has worked for three (3) years on Saudi ARAMCO CSD Geotechnical projects as a Geotechnical reporting and design Engineer. Currently, he is a postgraduate researcher at the Civil and Environmental Engineering Department, King Fahd University of Petroleum and Minerals (KFUPM), Dhahran, Saudi Arabia. His postgraduate studies are mainly focusing on unsaturated soil mechanics, granular material behaviour, slope stability, foundation design, DEM and FEM, and molecular/Nano simulation in Geotechnical and Geoenvironmental applications.
Omar S. Baghabra Al-Amoudi is currently the Dean of Educational Services and a Professor in the Department of Civil & Environmental Engineering at King Fahd University of Petroleum and Minerals (KFUPM), Saudi Arabia. Prof. Al-Amoudi obtained his BSc., MSc. and Ph.D. degrees (All with the first honour) from KFUPM in 1982, 1985 and 1992, respectively. He was one of the founding members of the American Concrete Institute-Saudi Arabia Chapter (ACI-SAC). Prof. Al-Amoudi has authored >180 papers in reputed journals and conferences. He won three regional awards and one international (CANMET-ACI) award. He has been the Editor-in-Chief of the Arabic Journal of Building Technology.
Knowing that not all clients are the same and that all applications differ was the driving force behind the MAX Plant range of equipment. From the beginning the team at MAX Plant looked at innovation as the driving force and how the portability can make a difference to the capital costs of setting up a mineral processing plant, whether in a mining application or a quarry application the MAX Plant product range has the solution. Below is a selection of previous MAX Plant projects
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