1. In-situ Leaching 2. Dump Leaching 3. Heap Leaching 4. Percolation Leaching 5. Agitation Leaching 6. Pressure Leaching

Hydrometallurgy Flashcards by RevicVince Rosales

the production of metals from
primary and secondary
metallurgical sources wherein
some of the chemical reactions
are carried out in aqueous
solutions at ambient temperature

Hydrometallurgy

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Hydrometallurgy

Temp:

less than 300 degree C

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Hydrometallurgy

Pressure

less than 2.07 MPa

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ADVANTAGES of METALLURGY

a. have the ability to treat ores
b. may eliminate the requirements of waste
disposal
c. enables one to avoid emission of sulfur in
gaseous form

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Advantages of Metallurgy

❖ minimum environmental impact; and
❖ no solid disposal problems

b. may eliminate the requirements of waste disposal

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Advantages of Metallurgy

can improve the logistics and economics of
metal/mineral Extraction

a. have the ability to treat ores

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Advantages of Metallurgy

❖ protects us from acid rain

c. enables one to avoid emission of sulfur in
gaseous form

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most commonly used in GOLD hydro

Cyanidation

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APPLICATIONS

90% production of ________

GOLD

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80% production of ____

ZINC

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APPLICATIONS

Production of ______

NICKEL AND COPPER

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100% production of ____

ALUMINA

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GENERAL STEPS

1 MINERAL BENEFICATION
2 ROASTING
3 LEACHING
4 SOLID/LIQUID SEPARATION
5 METAL/ MINERAL RECOVERY
6 SOLID/WASTE TREATMENT

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What are the solid/waste treatment for sample?

Tailing Storage Facilities (TSF)

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CHOOSING HYDROMETALLURGY

KADTONG 5 KABUOK YOT

The amount of valuable mineral in the
deposit
Amenability of dissolving the valuable
mineral using available solvents
Presence of volatile toxic elements upon
melting, i.e. As, Sb, Pb, Hg
Cost of mining and bringing the ore to
the surface
Cost of milling and other pre-leaching
treatments

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+Process of dissolving valuable minerals or
metals from an ore or concentrate feed and
extracting the metals of interest into the
solution
+Feed may also be secondary sources
(scraps)
+Metallic ions are extracted in the leach
liquor, leaving a residue or gangue, free of
the valuable minerals

LEACHING

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Choice of leaching methods depends on:

oOre grade
oLeaching kinetics
o Reagent consumption
oType of minerals
oSize of operation
o Capital and operating cost

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TYPES OF LEACHING

In-situ Leaching
Dump Leaching
Heap Leaching
Percolation Leaching
Agitation Leaching
Pressure Leaching

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APPLICATIONS AND TECHNIQUES SA IN-SITU LEACHING

LAST FOR???

APPLICATION
a. Near-surface low grade ore
b. deep seated high grade ore

TECHNIQUES
a. stope leaching
b. bore-hole solution

YEARS

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APPLICATIONS AND TEACHNIQUES OF HEAP LEACHING

LAST FOR???

APPLICAITON
a. mined low grade ore
b.20 cm in diameter

TECHNIQUES
a. piled into heaps on impervious ground
b. solvent is allowed to permeate the heap

MONTHS

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APPLCATION OF DUMP LEACHING

IT TAKES????

APPLICATION
a. stripped marginal deposition

TECHNIQUES
a. dumping in the foot or cliff
b. leaching agent is sprayed on it regularly

YEARS

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Stirred tanks with or without air

AGITATION LEACHING

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APPLICATIONS AND TECHNIQUES OF PERCOLATION LEACHING

LAST FOR?

APPLICATION
a. porous and sandy material
b. regular size at 5mm diameter

TECHNIQUES
a. does not need S/L separation
b. counter current leaching

WEEKS

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APPLCIATIONS AND TECHNIQUES OF AGITATION LEACHING

LAST FOR?

APPLICATIONS
a. particles with 0.5 mm or less in diameter
b. slurry is introduced in the process
Counter Current

TECHNIQUES
a. Mechanical agitation
b. compressed air agitation
c. COmbined mechanical and compressed-air

DAYS

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UNSAY GINAGAMIT SA PRESSURE LEACHING???

AUTOCLAVES

APPLICATIONS AND TECHNIQUES OF PRESSURE LEACHING ## Footnote LAST FOR

APPLICATION a. Minerals that are difficult to dissolve at STP TECHNIQUES a. mechanical agitation b. compressed air agitation c. combined mechanical and compressed-air ## Footnote HOURS

Choosing a solvent ## Footnote 5 ni sila

1. Readily available 2. Relatively cheap 3. Selective in its dissolution 4. Non-corrosive to construction materials 5. Easily regenerated in the operation

Choices of Solvents: ## Footnote 5 pud ni sila yot

1. Aqueous salt solutions 2. Chlorine water 3. Water 4. Bases 5. Acids

+Must be able to withstand the pressure produced from the evaporation of the leaching agent since operation is done above the boiling temperature of the leaching agent * When under oxidizing atmospheres, it must be able to withstand the additional pressure of the heated air or gas

AUTOCLAVES

OBJECTIVES SA ENRICHMENT PROCESS

produce smaller volume and richer pregnant solution

# METHODS ION EXCHANGE

FUNCTIONALIZED RESIN

# METHODS ADSORPTION

ACTIVATED CARBON

# METHODS SOLVENT EXTRACTION

ORGANIC SOLUTION

+the attached functional groups in the resin undergo ionization to yield cations (or anions of an anion exchange resin) that selectively exchange with other ions present in the solution in which the resin is immersed

ION EXCHANGE METHOD

allow gold to enrich during the process

ION EXCHANGE METHOD

Dilute pregnant solution apply activated carbon so mabawasan si barren solution

SORPTION

2 types of ADSORPTION METHOD

SORPTION ELUTION

stripping solution to get enriched pregnant solution

ELUTION

+the solid carbonaceous material coal such as coal, wood, nut shells, sugar, synthetic resins pyrolyzed at about 600oC in the absence of air

CARBONIZATION

The activated charcoal is a highly porous carbon material made from coal, wood, sugar, synthetic resins and nutshell

ACTIVATED CARBON

+Carbon is exposed to steam or air for a limited time at temperatures between 400 and 800oC

ACTIVATION

Properties of AC

+hard and abrasion resistant +large surface area of 1200 m2/g +high porosity at 0.7-0.8 cm3/g with 95% macropores, then the remainder comprises of meso- and micropores +can act as reducing agents to metals in salt solutions:

Methods of Adsorption

+Carbon-in-Leach +Carbon-in-Pulp +Hybrid CIL-CIP method

+carbon adsorbs the gold cyanide complex from the slurry solution and is then removed by coarse screening +6 tanks for leaching +followed by 4-6 tanks for adsorption

Carbon-in-Pulp (CIP)

+adsorption is limited in the first tank +carbon loading is 20- 30% less +often used for carbonaceous gold ores

Carbon-in-Leach

+Similar to CIP process except that activated carbon is used to extract gold from gold cyanide solution streams, such as: oHeap or dump leach solutions oThickener overflow solutions oUnclarified filtrates oTailings reclaim solutions

Carbon-in-Solution

+Modified CIP process +leaching and adsorption occurs simultaneously +– in a series of tanks, i.e. 6 tanks, the slurry is introduced into the 1st tank while the AC is introduced in the last tank (counter-current)

Carbon-in-Leach (CIL)

the loaded carbon is heated by a strong solution of hot caustic and cyanide to reverse the adsorption process and strip the carbon of gold

ELUTION or STRIPPING

* immediately maximizes the available surface area of the activated carbon

Carbon-in-Pulp

* pretreat loaded AC with strongly alkaline cyanide solution to convert calcium aurocyanide complex to sodium form * elution with deionized water at a temperature of 95 – 125oC

DAVIDSON PROCESS

* loaded carbon is soaked in a 1.5 – 5% NaCN and 0.5 – 2% NaOH solution for several hours at temp. greater than 90oC * Au and Ag is eluted with several bed volumes of hot distilled water * Reduced cycle time to 12 hrs

AARL – MODIFIED ZADRA

(US Bureau of Mines, late 1960’s) * insulated tank * 90 – 93oC working temp * 0.2% NaCN * 1% NaOH * flow rate: 1 bed vol/hr

ZADRA PROCESS

* uses an addition of 20% alchohol to the Zadra elution solution * elution is accomplished at 80oC for 6 – 8 hrs * the alcohol used are ethyl, methyl, and isopropyl

DRUNKEN ZADRA

* elution is carried at 145oC which simply means that elution is pressurized * elution time is 12 hours

PRESSURE ZADRA

+a distributive reaction wherein the valuable metal is allowed to partition itself between two immiscible phases with the eventual establishment of equilibrium

Solvent Extraction

- are organic solvents in which the extractants are soluble - are immischible with water - constitue the bulk of the organic phase - are not able to extract metal ions but could influence behavior of extractants; inert component of the organic phase

Extractant + Carrier

* the formation from solution of a solid product as a result of dilution or of the addition of a reagent to the solution

Precipitation

Factors affecting Precipitation

a) pH b) temperature c) complexing ions d) concentration of the reactants

# factors sa precip precipitates are only formed within a certain pH range, since most of them are redissolved outside this range

most precipitates are either more soluble in hot than in cold solutions or decompose when precipitation is carried out at high temperatures

temperature

the presence of a complexing ion in solution prohibits the precipitation of the metal with which it is complexed

complexing ions

large crystals are obtained by precipitation from dilute solutions; fine precipitates are obtained from supersaturated solutions

d) concentration of the reactants

+IONIC PRECIPITATION +PRECIPITATION BY GASES +PRECIPITATION BY METALS

Methods of Precipitation