Description of Gold

Gold is a soft yellow metal which is much heavier than a normal stone of the same size. It is non-corrosive, non-magnetic. However, gold is very good conductor of heat and electricity and it does not change its state or color even when exposed to the nature for millions of years.

Gold is valuable and can be a substitute for money in trade. Gold is like money and it is used as a financial instrument and is readily traded throughout the world. It has a well-publicized price. Gold is mined and recovered by utilizing different mining and processing techniques. 

It can be mined by locals using small scale mining methods for alluvial or mined from hard rock gold deposits using highly mechanized operations or from placer deposits using simple or semi mechanized alluvial mining techniques.

Some minerals can be misleading. i.e. pyrite will look similar to gold but you need to know very well the properties of gold in terms of shape patterns and appearance. Pyrite is actually a fools gold.  First timers need to be very careful if you are buying gold from alluvial gold miners. There are other various techniques which you can use to identify and be sure that what you see is for sure gold. Stay in tune or subscribe for updates on the next article(s)

Photo Courtesy of Gem Rock Auction

Reference:

Small Scale Gold Mining in Papua New Guinea, Department of Mining Papua New Guinea 2001.

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Environmental Impacts of Artisanal and Small Scale Gold Mining in Papua New Guinea

Mechanize Small Scale Mining

Artisanal and small scale gold mining (ASSM) offers lucrative employment opportunities to the locals of most developing countries. The major drawback of ASSM is its impacts on the environment as a result of improper mining and processing techniques. Exposed and disturbed lands are usually subject to soil erosion and avalanches of debris in active ASSM areas. Mercury is commonly used to concentrate gold, and if not handled properly causes pollution of life supporting river systems.

Small scale gold miners in many developing countries rely primarily on deposits containing free gold and may be classified as shallow/deep alluvial or lode type. The mining method used in artisan small scale gold mining employ very basic technology. Shallow alluvial deposits are commonly found in valleys and streams at depths not more than two meters. Deep alluvial deposits are found along major riverbanks and older river courses, and usually at depths exceeding six metres along the banks of rivers. The lode type of gold deposits is usually composed of partially weathered gold bearing reefs, which are either outcrops or near surface deposits. In Papua New Guinea, active artisanal mining are commonly found abandoned mining areas like Panguna and Missima and also near operating mines like Porgera, Eddie Creek in Wau Bulolo, Morobe Province. Not only that but also other parts of the Provinces also have active small scale miners. Other provinces include but not limited to: East Sepik, Sandaun, Enga, Western, Eastern Highlands, Jiwaka, Madang, Western Highlands, Oro, Milne Bay,Morobe.

 The small scale gold fields are mainly riverine deposits where mining occurs along river banks, terraces and in active river channels. Using poorly constructed sluice boxes, gold bearing material is fed into the inclined sluice boxes. The box is constructed using plywood or flattened roofing iron with wooden/metal ripples. These types of operations are associated with low to very low recovery because of uncontrollable river flow rates, incorrect inclination of the sluice boxes and inappropriate amounts of feed material at any one time. It is extremely difficult to introduce mechanised alluvial mining because of low skills and knowledge, isolation from transport infrastructure and lack of basic infrastructure.

The gold bearing gravels are concentrated by rippled sluice boxes. The fine gold is not commonly trapped in the ripple compartments. The fine particles of sand with gold in it are than poured into the panning dish for further panning. Mercury is placed in into the panning dish to concentrate the fine gold particles. Amalgamation is an efficient mean of extracting gold particles from concentrates after panning or sluicing.

In PNG small scale mining operations, the concentrates from sluicing operations are mixed with mercury in gold dishes or in sluice boxes. Mechanised concentrating equipment like the shaking table and Nelson concentrators are other options that few small scale miners are looking at. 

Health and environmental impacts (Watch Video)

The artisanal and small scale gold mining provides employment at local and national levels, and the sector is an important source for the inflow of foreign exchange into rural communities. However, small scale mining activities are associated with sensitive health and environmental issues.

The process of recovering gold by retorting and heating the amalgam over an open fire is a dangerous practice. The open fire could be in houses or at river banks and thus a whole family could be exposed to poisonous mercury fumes.

Concentrate from sluicing near streams is usually mixed with mercury and a considerable amount of mercury is lost to the streams. Apart from direct inhaling of mercury fumes by miners, aquatic life also feeds on mercury lost into the river, which are then eaten by the locals through the food chain. The Watut and Bulolo Rivers has been subject to prolonged mercury contamination and discharges of hydrocarbon wastes. The Watut people depend on the river for fishing, washing and farming on the river banks.

Some miners in old shafts and adits and they are consequently exposed to the trapped noxious gases such H2S. Locals have been reported that they are buried alive when they burrow through soft oxidized lodes or vein systems.

Some operators locate their sluice boxes in streams, thus polluting the water. Silting and stream discolouration are very common. Farmlands are usually destroyed by mining activities. Locals even uproot big trees along structurally defined thin gold deposits. Sometimes, the narrow gullies are not rehabilitated and are left to be taken care of by nature.

Exposed and disturbed lands are subject to soil creep widening the flow channels, and debris avalanches are common along rivers at the active mining areas. The loss of fertile land due to small scale mining puts socio-economic pressure on the local society. Old gravel pits are usually abandoned without reafforestation. Pits filled with stagnant water are common.

Education and training

Small-scale mining technology in most developing countries is simple and attracts many unskilled people. The desire for economic and social survival has attracted many people to the industry. The law expects the licensed small-scale miner to mine using effective and efficient methods, and observe good mining practices, health and safety and protect the environment.

The Small Scale Mining Branch of PNG Mineral Resources Authority (Formerly Department of Mining) in Wau, Morobe Provine has created education and training materials for the miners. The Department has produced seven booklets and DVDs on

• Simple Gold Mining;

• Basic Mining Practice;

• Advanced Mining practice;

• Handling of Mercury;

• Occupational Health and Safety;

• Environmental Issues; and

• Economics of Mining.

The major focus of the training resources is to ensure that small scale operations are safe, environmentally friendly and economically viable.

Small-scale mining operations in most developing countries have serious negative environmental impacts. One of the major factors is the implementation of the associated mining Acts  which are lacking.

Donor agencies like the World Bank, European Union and Japanese International Cooperation Agency (JICA) have in recent times shown keen interest in the negative and positive impacts of the PNG’s ASSM sector. AusAid and the World Bank have sponsored the building of the ASSM sector capability in PNG through legislative framework and training and awareness on the use of mercury.

Note: This article is a reproduction of a learning material with inclusion of up to date information.

Reference

[1] Ail, K. K. (2005. Kwoe River Alluvial Gold Deposit Evaluation and Development Plan, PNG University of Technology, Lae.

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Osarizawa Mine in Akita Prefecture, Japan

Osarizawa Underground Mine Adit

Osarizawa mine is an abandoned mine in Akita Prefecture, Japan. Event though the mine is closed, the mine site is kept for sightseeing purposes.  The Osarizawa mine deposit is a vein type deposit  which was  discovered in 708. The oldest Literature of the mine was written in 1599 about the discovery of the Gojumaizawa gold deposit which is part of the mine. The main commodities produced by the mine were gold and copper.

The vein deposit was mined using the shrinkage stope mining method. There are 15 levels and are 30m apart in height. The Total perimeter of the mine levels is 700 km. The area of the mine site is 3km N-S by  2km E-W ~ 6km² . Ceiling is 2-3m in width.   

The Level Zero starts at RL of about 300m and this is where the access adit (ingress) is built.  There are 5 levels above the  zero level and 10 levels below zero level. The mining progressed upwards and mined materials were collected at lower levels with the aid of gravity.

The host rock of the ore deposit is silicate mudstone which is 10 times harder than concrete. Since the host rock is highly competent, the mine was almost unsupported and less artificial support. Few supporting materials used were logs/timbers of about 10mm to 300mm in diameter which were fitted well in between mined out areas to prevent wall collapse. Other artificial supporting methods are roof bolts, Mass wires and steel spiral cables drilled upwards to prevent rocks from falling. Timbers are replaced every 10 years. The other supporting method used was the backfilling of mined out areas with waste materials. Underground water is effectively under control by plastic roofing gutters and drained out along the side of the concrete pathway at each level.

The mined out ore/materials were transported by mini rail cars which are powered by batteries. The rail cars were attached to one another like train cars. The railways were built for these small battery powered rail cars. The drilled or broken ores were loaded onto the rail cars and it required either one or two operators to transport the materials out of the mine via shaft by way of hoisting. At Zero Level the rail cars were driven out via the adit and further to the processing plant for processing.

 Production increased with the increase in the rail cars.

Note:This article is an observation report and may not contain factual and detail information. The information here is kept at high level only. This article is subject to change if need be.

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Applications (Uses) of Zeolites in Civil Construction and other Fields

Besides the widely usage of zeolites in the Livestock and Agriculture Industries, it is also utilized in the civil constructions and other technological fields as well.

To begin with, zeolites can also be used for separating oxygen and nitrogen in the air to produce oxygen-enriched gas. This technology utilizes the strong absorbability of mordenite to nitrogen molecules to generate oxygen continuously which is vastly depend on the device and can also produce nitrogen as well.

Zeolite rock/ore is generally soft but not fragile is used as teaching material for carving for school children and is also used as cleanser.

One of the new applications of zeolites is in food packaging materials that are made of polyethylene film incorporated with zeolites was developed with an aim to retain the freshness of food or fruits and vegetables.

One of the most important applications of zeolites is in the civil constructions. In civil constructions, zeolites are used as new lightweight building materials such as plastic filler and plywood adhesives. Further to the lightweight, zeolites are also used as foam blocks incorporated in linings of chimneys of thermal plants and dolomite plaster.

Similar to zeolite, siliceous mud-stone is utilized in such applications as soil conditioners, deodorizers (for environment improvement of poultry and pig farms), and special fertilizers.

Siliceous mudstone is also referred to as “crystobal rock” which contains a lot of crystobalite composed of silica (SiO₂).

Zeolite is used in a wide range of applications and among them is the clay for papermaking which was developed in Japan. Zeolite is soft and its powder is significantly white and it is applied to papermaking to take advantage of its properties. Zeolite clay is serving as a filter which provided paper with high opacity and excellent ink acceptance.

Synthetic zeolite was invented by German Professor Gans in 1905, and was first named permutit and after permutare, a Latin word meaning exchange. Permutit has a composition of Na₂O.Al₂O.xSiO₂.yH₂O and strong adsorbability.

Crushed Zeolite Materials ready for loading

References:

Boiling stone (zeolite), Zeolite Dynamics, Lecture Notes.

Nouko to Engei (Agriculture and Horticulture), September 1978.

JACK News

Materials for Zeolite Forum (1989)

Survey by Zeolite Industrial Association

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Applications (Uses) of Zeolites in the Livestock and Agriculture Industries.

Zeolites are widely used in the livestock and agriculture industries among other uses. In this article, it discusses the common uses of zeolites in the livestock and agriculture industries. In the Livestock Industry, zeolite is purposely used for improving the growth and health of animals while in the Agriculture Industry, zeolite is used for the purpose of improving the fertility of the soil for healthy growth of cash crops.

The use of zeolites in the livestock industry is basically added to the livestock feed which absorb the toxins in the body of chickens and pigs and finally discharge them out of the body.

Furthermore, the minerals contained in the zeolites actually promote the growth and health of livestock. That is, zeolites adsorb the stench of ammonia to improve the environment and also function as drying aids by virtue of their ability to absorb moisture. Thus, cat litter (litter for pets) utilize such properties of zeolites for optimum benefits.

In the Agriculture Industry, it utilizes the properties of zeolites such as the adsorption capability and Base Exchange capability which prevent the outflow of fertilizers by absorbing the components of fertilizers as well as improving soils by neutralizing soils containing acids or acidic soils. Zeolites also have excellent absorption ability and water retention capacity which make them more effective in preventing either drought or cold weather impacts of any kind cause by nature.

Estimation of cation exchange capacity of zeolite is much more difficult as it is closely related with qualities from its appearance. As such, zeolite powder is not readily distinguished from other rock powder.

Zeolite is specified as land improvement material by a Cabinet Order based on the Soil fertility Enhancement Act (Act No.34 of 1984) in order to assure the quality. According to Cabinet Order, the zeolite must meet the criterion “cation exchange capacity (C.E.C.) per 100 g of dry matter is 50g or more.”

Moreover, the applications or uses of zeolites range from water purification for fish farming to pollution prevention exercises. The water purification for fish farming refers to a function to adsorb ammonia and hydrogen sulfide in water which produces purified water.  In addition to that, zeolites have an effect of softening hard water to stabilize pH.

Besides water purification for fish farming, zeolites are also used for pollution prevention in the following fields:

·         Purification of hazardous components in industrial wastewater.

·         Adsorption treatment of heavy metal ions from abandoned mines.

·         Removal of heavy metals from plating waste.

·         Decolourization of waste water from dye houses.

·         Prevention of eutrophication of lakes and marshes caused by ammonia nitrogen.

·         Removal of harmful components from automobile exhaust gas.

The supply of zeolites depends entirely on clients' demand and off course consumption rate. Supply of zeolites is also dictated by scale of mining operation and processing.

Zeolite ore (rock)

References:

Boiling stone (zeolite), Zeolite Dynamics, Lecture Notes.

Nouko to Engei (Agriculture and Horticulture), September 1978.

JACK News

Materials for Zeolite Forum (1989)

Survey by Zeolite Industrial Association

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Data Analysis of Rapid PACKTEST Results

Upon the completion of the setup and PACKTEST, you have the data available at hand to record. In your note book you record the readings of pH, Turbidity, Temperature, metal conductivity. Then you have the other sets of data from the PACKTEST results. Each element tested has got a numbered color range that corresponds to the concentration of that element/compound in the water sample. You record every data for the elements that are tested.

Finally, you need to digitize the data and analyze the test results. To do that, you need to have a computer or a laptop. Create an excel spread sheet in your laptop or computer and enter the field data in a tabulated format. Your sample results look like the table below:

Table 1 Rapid PACKTEST Results

Now, data analysis is the comparison, verification and few comments or conclusion drawn from the raw data collected from various spots/sites which are tabulated like Table 1 (above). A good analysis of data/ results is always a careful comparison and contrast in the data obtained by plotting the data in different graphical methods.

Be careful to graph the related data so that any conclusion drawn can make sense with respect to particular information. i.e. if you plot all the data into one graph then always take note of the legends so that your interpretation is accurate in reporting.

It is also better to take readings at different weather patterns i.e. during rainy seasons and dry seasons. Remember to keep the sample points unchanged so that a good comparison is made.

From the data analysis, it is better to make few comments and off course a recommendation is anticipated from the field investigation. Your recommendation should provide a clear direction/ indication should there be precautions taken within the vicinity of the impacted project area especially the mine impacted communities. Your recommendation should also alert the local government authorities regarding the findings and what to do in that part of the area.

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Characteristics of Zeolite Ore

• Like any other matters, Zeolite has two major characteristics which are:

1.      a chemical composition having zeolitic water, and

2.      An excellent ion exchange capability.

Zeolitic water is unique in the composition which is hardly observed in other minerals, as dehydration occurs without changing the crystal structure under heating. This hydration behaviour enables zeolite to be used as moisture absorbent.

In addition, the dehydrated zeolite has a myriad of holes like a honeycomp and the holes have such small sizes in the order of angstroms (Symbole:Å, unit cm/100 million). Accordingly a mixture of gasses with different molecular sizes, which are chemically difficult to separate at the molecular level, can be sieved through zeolite. This is called the “molecular sieve effect.”

The Cation exchange capacity of zeolite is explained as follows:

The general chemical composition of zeolite in general is indicated by

(M²⁺,M₂₊)O.Al₂O₃.mSiO₂.nH₂O. The symbols in the parentheses at the beginning of the formula indicate exchangeable cations. Cations in zeolite are exchangeable with other cations in aqueous solutions. In chemical terms, material with a positive charge is referred to as a base. The ability to exchange bases is Base Exchange capability (or cation exchange capability), while the capacity to exchange bases is base exchange capacity (or cation exchange capacity) and is called C.E.C., the acronym for “Cation Exchange Capacity.”

Ion exchangeability allows silicon (Si) atoms located in the centre of the zeolite crystal lattice to be partially replaced with aluminium (Al) atoms, resulting in the loss of cations. Cations such as sodium (Na), Calcium (Ca) are captured in the crystal lattice to compensate for the shortage.

The function of C.E.C. is similar to that of the liver of an animal which stores nutrients. Zeolite adsorbs and stores fertilizer components (bases) such as sodium, potassium and calcium to supply the nutrients (fertilizer components) to crops in response to request.

The unit of cation exchange capacity is represented by mg equivalent (meq) per 100g of soils or zeolite rocks.

The cation capacities of clay minerals are different depending on the type of minerals. Montmorillonite is the main mineral source for bentonite which exhibits the highest C.E.C. after zeolite.

Reference:

Boiling stone (zeolite), Zeolite Dynamics, Lecture Notes.

Roskill Report (1990)

Annual Reports of Various Companies.

Nouko to Engei (Agriculture and Horticulture), September 1978.

JACT News.

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Localities of Zeolite Ore

Since all Zeolites are alteration products of volcanic glass present in tuff (a rock containing consolidated volcanic ash) or tuff breccia (rock consists of volcanic rocks cemented together by large amount of volcanic ash), the ore does not consist solely of zeolite, and thus it is appropriate to be called zeolite-containing tuff.

Zeolite resources can be found in sedimentary layers or rocks of volcanic ash throughout the world. Natural zeolite deposits have recently been discovered in the Pacific Rim countries, including New Zealand and countries of Mediterranean coast.  Among these countries, Japan has been leading the rest of the world in the exploration and development of natural zeolite and has been the world’s major producing countries.

Localities of Natural zeolite in the United States are distributed mainly in the western states such as Oregon, Nevada, California and Idaho. Most of the mines produce clinoptilolite and mordenite

Apart from United States and Japan, zeolite is also discovered in Eastern European countries which include eastern part of Czechoslovakia, the north-eastern part of Hungary, the north-western part of Yugoslavia, and south-eastern part of Bulgaria. And also countries like Italy, Cuba, Brazil, South Africa and China are all recorded as zeolite producing countries.

Australia recently started producing natural zeolite in Werris Creek, South of Tamworth in New South Wales as well as Cranky Corner near Singleton.

Zeolite is purified differently depending on the nature of the ores and is associated to the processes of granulation, drying, milling, screening (sizing) and bagging. Special applications such as filler for high-quality paper, after milling, the zeolite is subject to wet process of bleaching, concentration, filtering and finally drying.

Zeolite boulders

Reference:

Boiling stone (zeolite), Zeolite Dynamics, Lecture Notes.

Roskill Report (1990)

Annual Reports of Various Companies

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Zeolite (Boiling Stone) Ore

Zeoilte (Boiling Stone) Ore

Zeolite is a term referred to as Boiling Stone. The Term Zeolite is derived from two Greek words Zeo (to boil) and Lite (a stone).  The heated ore supported at the tip of a blowpipe which is used for qualitative research is observed to swell into a pumice-like porous state when air is blown from the mouthpiece. The phrase boiling term comes from this behaviour.

Zeolite is an aluminosilicate mineral (silicate in which silicone atoms are partially replaced with aluminium atoms) containing maily alkali metals such as sodium and potassium and alkaline earth metals such as calcium and magnesium, as well as water molucules (H₂O) in the form of crystals.

(M²⁺,M₂₊)O.Al₂O₃.mSiO₂.nH₂O

M^2+: Mainly Calcium (Ca)

M⁺: Mainly Sodium (Na), Potassium (K)

Zeolite commonly occur in pores of volcanic rocks or inside the rocks in the shape of veins, and are found in the strata near metal ore deposits as well as geothermal power plants and hot springs. Volcanic glass in tuff often transforms into zeolite under the influence of seawater. As a result, besides pure zeolite components, zeolite rock contains minerals such as clay (montmorillonite), iron oxide and feldspar.

Generally, zeolite will generate different zeolite crystal structures, even if it is from the same origin rock, depending on the burial depths, with the pressure on the rock increases to affect the crystal structure with and aid of ground water and hot water. Natural

Among many minerals, the widely distributed natural zeolites are clinoptilolite (often called ‘clino’) and mordenite.

Laumontite is a white plate-like or columnar crystal. Laumontite, which is formed primarily by the action of hot spring water, replaces minerals in rocks or fill cracks making a pattern of veins. Laumontite can be found in aggregates (or gravel) in concrete.

Laumontite is said to react with alkali in cement (alkali-aggregate reaction) to inflate the aggregate which cause cracking.

Applications of zeolite will be in the next article.

Reference: Boiling stone (zeolite), Zeolite Dynamics, Lecture Notes.

Zeolite ore 

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How to Conduct Rapid PACKTEST in a Well (below 1 meter in depth)

Well is simply a shaft sunk into the ground or built upwards from certain depths below a natural surface of the ground which extends further above certain heights of the natural surface of the ground 

Wells can be naturally occurring or man-made. Man-made wells are created to suite the desired purpose(s) of the organisation or individuals. Wells can be created to collect water or oil or gas below the earth’s surface.

In a mining operation, wells are created for the purposes of heap leaching through a vat. Heap Leaching is one of the various mining techniques to extract gold from the ore of various host rocks using cyanide which is one of the common solvent in this gold recovery technique.

During the gold recovery process, cyanide is sprinkled over the heap of crushed gold bearing gravels (ore) to dissolve the gold into a pregnant solution or into liquid form. The pregnant solution is then sucked out through the vat and further into carbon columns and take to the processing plant for further processing and smelting.

Upon the closure of the mine, the vats are no longer in use. Cyanide is left behind the pool beside the heap-vats eventually gets into the surrounding environment which is a concern for mine waste management. Water is then filled through the Vats up to certain heights.  So from the top and surface of the heap-vats, the water level is below certain depths of about 2 – 3 meters which are hardly reached by hand. And also the diameter of the vats is about 30-40 cm which is too narrow to be accessed. So how can you how can you overcome this challenge to take a water sample for a Rapid PACKTEST as well as other measurements?

The simple way to get sample is by utilizing the following equipment procedures:

1.     String line (rope)

2.     Metal weight(1kg weight)

3.     3x1 Litre plastic bottle(container)

4.     Masking tape

5.     Water level measuring tape

6.     GPS

7.     Note book, pen, pencil

8.     Camera

9.     Blade/kitchen knife

10. PACKTEST kits

11. Syringe

12. 0.45µm filter

13. turbidity meter

14. pH meter

15. Laptop/computer

 Procedure

1.     Cut the 1 Litre plastic bottles (container) into more than half.

2.     Tie the 1kg metal weight at the tip of the string line.

3.     With the masking tape, fasten the cut container with the weight attached to the string line.

4.     Drop the container attached to the weight and stringline into the well and allow the container to be filled with water.

5.     Pull the string line with all its attached items and pour the fetched water into the other reserved containers.

6.     Never forget to measure the water level by using the 50m water level measuring tape.

7.     Using the GPS you take the readings of sample location coordinates and altitude and location zone.

8.     Finally , you conduct Rapid PACKTEST and

9.     Turbidity and pH measurements, conductivity and temperature readings as well.

The above procedure can be repeated for wells or pools that are hardly accessible in person or by hand.

Data Collection of the Rapid PACKTEST is the final thing to do before moving to the next location or ending the field work.

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