Export your learner materials as an interactive game, a webpage, or FAQ style cheatsheet.
Unsaved Work Found!
It looks like you have unsaved work from a previous session. Would you like to restore it?
Total Categories: 5
Hydrometallurgy, a sub-discipline of extractive metallurgy, exclusively employs high temperatures as its primary methodology for metal recovery.
Answer: False
This statement is incorrect. Hydrometallurgy is fundamentally characterized by its use of aqueous solutions for metal dissolution and recovery, distinguishing it from pyrometallurgy, which relies on high temperatures.
Hydrometallurgy is primarily utilized for the extraction of common base metals such as iron and aluminum.
Answer: False
This assertion is incorrect. While hydrometallurgy can be applied to various metals, it is particularly significant for the extraction of less common or more complex metals, such as rare earth elements and uranium, and is often used for copper and gold. Iron and aluminum are predominantly extracted via pyrometallurgical or electrolytic processes, respectively.
The chemical compound represented by the formula [Au(CN)₂]⁻ is formed during the pyrometallurgical processing of gold.
Answer: False
This statement is incorrect. The dicyanoaurate(I) complex, [Au(CN)₂]⁻, is characteristic of the hydrometallurgical process of gold cyanidation, not pyrometallurgy.
Pyrometallurgy serves as a complementary technique to hydrometallurgy by employing high temperatures for metal extraction.
Answer: True
This is accurate. Pyrometallurgy, which utilizes thermal processes, is a significant branch of extractive metallurgy that often complements hydrometallurgical methods, addressing different ore types or stages of metal production.
Water is the predominant solvent utilized in the majority of hydrometallurgical processes.
Answer: True
This is correct. Water serves as the primary solvent in most hydrometallurgical operations due to its availability, cost-effectiveness, and ability to dissolve a wide range of inorganic compounds, often with the addition of acids, bases, or complexing agents.
The Extractive Metallurgy Navbox categorizes processes into pyrometallurgy, hydrometallurgy, and electrometallurgy exclusively.
Answer: False
This statement is incorrect. The Extractive Metallurgy Navbox typically includes 'Mineral Processing' as a distinct category alongside pyrometallurgy, hydrometallurgy, and electrometallurgy, as it deals with the physical separation and concentration of valuable minerals before chemical extraction.
Smelting and cupellation are examples of hydrometallurgical techniques.
Answer: False
This is incorrect. Smelting and cupellation are classic examples of pyrometallurgical processes, involving the application of high temperatures to extract and refine metals, rather than the use of aqueous solutions characteristic of hydrometallurgy.
The Hall–Héroult process is mentioned as an example of electrometallurgy.
Answer: True
This is correct. The Hall–Héroult process, used for the electrolytic production of aluminum from alumina dissolved in cryolite, is a prominent example of an electrometallurgical technique.
The chemical formula [Au(CN)₂]⁻ represents the compound iron sulfide.
Answer: False
This statement is false. The formula [Au(CN)₂]⁻ represents the dicyanoaurate(I) complex, which is involved in the hydrometallurgical extraction of gold, not iron sulfide.
Which of the following best defines hydrometallurgy within the field of extractive metallurgy?
Answer: A technique employing aqueous solutions to dissolve and recover metals from sources.
Hydrometallurgy is precisely defined as the branch of extractive metallurgy that utilizes aqueous solutions to dissolve and recover metals from their ores and other sources.
What are the three primary operational areas into which hydrometallurgy is typically divided?
Answer: Leaching, Solution Concentration/Purification, and Metal Recovery
Hydrometallurgical processes are conventionally segmented into three principal stages: leaching (dissolution), solution concentration and purification, and final metal or metal compound recovery.
Which of the following is a technique that complements hydrometallurgy, utilizing heat for metal extraction?
Answer: Pyrometallurgy
Pyrometallurgy, which employs high temperatures, is a significant branch of extractive metallurgy that complements hydrometallurgy.
What is the most common solvent used in hydrometallurgical processes?
Answer: Water
Water is the predominant solvent in hydrometallurgy, serving as the basis for most aqueous lixiviant solutions.
According to the Extractive Metallurgy Navbox, which category includes processes like comminution and froth flotation?
Answer: Mineral processing
Comminution (size reduction) and froth flotation (separation based on surface properties) are fundamental techniques within the domain of mineral processing, which precedes chemical extraction stages like hydrometallurgy.
The process of dissolving metals from their sources utilizing aqueous solutions is termed 'metal recovery'.
Answer: False
This assertion is inaccurate. The process of dissolving metals from ores or other materials using aqueous solutions is specifically defined as 'leaching,' which is the initial stage in hydrometallurgical operations. Metal recovery is a subsequent stage where the dissolved metals are extracted from the solution.
A lixiviant is defined as a solid material employed in hydrometallurgy to absorb dissolved metals.
Answer: False
This statement is incorrect. A lixiviant is the aqueous solution used in the leaching process to dissolve and extract target metal ions from solid materials, not a solid absorbent.
Optimizing the effectiveness of a lixiviant involves meticulous control over parameters such as pH, redox potential, temperature, and the concentration of chelating agents.
Answer: True
Indeed, the efficacy of a lixiviant is significantly influenced by factors including its pH, oxidation-reduction potential, temperature, and the presence of specific chemical agents like chelating agents, all of which are carefully managed during process optimization.
In a conventional leaching process, the metal-bearing solution is separated from the solid ore residue via filtration.
Answer: True
Correct. Following the dissolution of metal ions into the lixiviant, filtration is a standard procedure to separate the liquid phase, now containing the dissolved metals, from the remaining solid ore particles.
Copper carbonate minerals, such as malachite, can be effectively leached using alkaline solutions.
Answer: False
This is incorrect. Copper carbonate minerals like malachite are typically leached using acidic solutions, such as sulfuric acid, which readily dissolve them. Alkaline solutions are generally not employed for this purpose.
Copper sulfide minerals are readily dissolved directly in aqueous solutions without any prior chemical or thermal treatment.
Answer: False
This statement is false. Copper sulfide minerals are characteristically resistant to direct dissolution in simple aqueous solutions. They typically necessitate pre-treatment, such as roasting, to convert them into more soluble forms before effective hydrometallurgical leaching can occur.
Heap leaching operations are characterized by the processing of ore within high-pressure reactors known as autoclaves.
Answer: False
This statement is incorrect. Heap leaching involves spreading crushed ore in large piles and allowing solutions to percolate through them. Autoclaves, conversely, are high-pressure reactors used for more aggressive leaching conditions, typically in tank or vat leaching, not heap leaching.
In-situ leaching, also referred to as solution mining, involves the extraction of metals from underground ore bodies without the need for excavation.
Answer: True
This is accurate. In-situ leaching, or solution mining, is a technique where the lixiviant is introduced directly into the subterranean ore deposit, and the resulting metal-bearing solution is then pumped to the surface for processing, thereby avoiding surface excavation.
In the context of heap leaching, the pregnant leach solution is collected from the upper surface of the ore pile.
Answer: False
This is incorrect. The pregnant leach solution, which is enriched with dissolved metals, is collected from the bottom of the ore heap after the lixiviant has percolated through the ore, not from the top surface.
Gold cyanidation, a common heap leaching practice, utilizes a strong solution of cyanide to dissolve gold from ore.
Answer: True
This is correct. Gold cyanidation is a widely employed hydrometallurgical process where a dilute cyanide solution acts as the lixiviant to selectively dissolve gold from low-grade ores, typically within a heap leaching configuration.
The purpose of a lixiviant is to precipitate valuable metals from a solution.
Answer: False
This statement is incorrect. A lixiviant's function is to *dissolve* and extract target metal ions from solid materials into an aqueous solution, not to precipitate them.
Copper sulfide minerals typically require roasting prior to effective hydrometallurgical leaching.
Answer: True
This is correct. Copper sulfide minerals are often refractory to direct leaching and require pre-treatment, such as roasting, to convert them into more soluble oxide or sulfate forms, thereby enhancing their leachability.
Filtration in a leaching process serves to separate the dissolved metal ions from the solid residue.
Answer: False
This statement is misleading. Filtration separates the *solid residue* from the *liquid solution* containing the dissolved metal ions. The dissolved ions themselves are not separated from the residue by filtration; rather, the liquid carrying them is separated from the solid.
What is the fundamental purpose of the leaching stage in hydrometallurgy?
Answer: To dissolve metal ions from solid materials into an aqueous solution.
The primary objective of leaching is to selectively dissolve target metal ions from solid ores or concentrates into an aqueous solution (lixiviant), thereby initiating the separation process.
How is a simple leaching process typically concluded before further processing?
Answer: The liquid solution containing dissolved metal ions is separated from the solid residue via filtration.
Following the dissolution of metals, a simple leaching process typically concludes with filtration to separate the pregnant leach solution from the residual solid material.
Why do copper sulfide minerals often require pre-treatment, such as roasting, before hydrometallurgical processing?
Answer: Roasting converts them into a more easily leached, soluble form.
Roasting transforms refractory copper sulfide minerals into more soluble oxide or sulfate compounds, significantly improving their amenability to subsequent leaching in aqueous solutions.
Which of the following is a method where the extracting solution is pumped directly into an underground ore deposit?
Answer: In-situ leaching (Solution mining)
In-situ leaching, also known as solution mining, is characterized by the direct injection of lixiviant into subterranean ore bodies to dissolve metals, which are then recovered from the pumped solution.
In heap leaching, what is the 'pregnant' leach solution?
Answer: The solution that has percolated through the ore and become enriched with dissolved metals.
The term 'pregnant' leach solution refers to the aqueous phase that has passed through the ore heap, having dissolved and thereby become enriched with the target valuable metals.
What is the primary role of a 'lixiviant' in hydrometallurgy?
Answer: To dissolve and extract target metal ions from the source material.
A lixiviant is the aqueous solution employed in the leaching stage, specifically designed to dissolve and extract the desired metal ions from the solid ore or concentrate.
Chelating agents are employed to decrease the solubility of target metals during the leaching process.
Answer: False
This statement is incorrect. Chelating agents are typically used to *increase* the solubility of target metals by forming stable complexes, thereby enhancing their selective dissolution and extraction from the ore matrix.
The solution concentration and purification stage in hydrometallurgy aims to remove valuable metals from the leach solution.
Answer: False
This statement is incorrect. The primary objective of the solution concentration and purification stage is to increase the concentration of the desired valuable metal ions and remove impurities, not to remove the valuable metals themselves.
Cementation involves displacing a less reactive metal ion in solution with a more reactive metal.
Answer: False
This statement is incorrect. Cementation is a process where a *more* reactive metal dissolves, displacing a *less* reactive metal ion from solution, which then deposits as a solid metal.
In solvent extraction, metal ions are transferred from an aqueous phase to an organic phase using specific extractant chemicals.
Answer: True
This is correct. Solvent extraction is a technique where specific chemical extractants dissolved in an organic solvent selectively bind to target metal ions, facilitating their transfer from the aqueous leach solution into the organic phase.
Di(2-ethylhexyl)phosphoric acid and tributyl phosphate are primarily utilized as diluents in hydrometallurgical solvent extraction.
Answer: False
This statement is incorrect. Di(2-ethylhexyl)phosphoric acid is typically used as an *extractant*, while tributyl phosphate can function as either an extractant or a diluent, but they are not exclusively diluents. Diluents are usually inert hydrocarbon derivatives.
Ion exchange materials are exclusively designed to adsorb positively charged ions (cations) from solutions.
Answer: False
This is incorrect. Ion exchange materials can be designed to selectively adsorb either cations (cation exchangers) or anions (anion exchangers), depending on the functional groups incorporated into the resin structure.
In solvent extraction, a diluent is the chemical compound that selectively binds to the target metal ions.
Answer: False
This statement is incorrect. In solvent extraction, the diluent is typically an inert solvent that dissolves the extractant and modifies the viscosity and handling properties of the organic phase. The *extractant* is the chemical species that selectively binds to the target metal ions.
Ion exchange resins are designed to facilitate the exchange of neutral molecules between a solution and the resin.
Answer: False
This is incorrect. Ion exchange resins function by exchanging *ions* (charged species), either cations or anions, between the solution and the functional groups attached to the resin matrix, not neutral molecules.
What is the function of chelating agents in the context of hydrometallurgical leaching?
Answer: To selectively bind with specific metal ions, enhancing separation.
Chelating agents form stable complexes with specific metal ions, thereby increasing their solubility and facilitating their selective dissolution and separation from other components in the ore.
Which process is used to recover copper from a solution by displacing it with scrap iron?
Answer: Cementation
Cementation is a redox process where a more reactive metal (like iron) dissolves, displacing a less reactive metal ion (like copper) from solution, causing the copper to deposit as a solid.
What is the role of the organic phase in solvent extraction?
Answer: To selectively transfer target metal ions from the aqueous phase.
The organic phase, containing specific extractants, is designed to selectively complex with and transfer target metal ions from the aqueous leach solution into itself, facilitating separation.
How does precipitation differ from cementation in hydrometallurgy?
Answer: Precipitation forms an insoluble solid from solution due to exceeding solubility, while cementation involves displacement by a more reactive metal.
Precipitation occurs when solution conditions cause a solute to exceed its solubility limit and form a solid. Cementation is a specific type of chemical displacement reaction where a more reactive metal replaces a less reactive metal ion in solution.
Precipitation is a technique employed to increase the concentration of metal ions in solution.
Answer: False
This is incorrect. Precipitation is a process used to form an insoluble solid from a solution when the concentration of a species exceeds its solubility limit, thereby *removing* it from the solution, not increasing its concentration.
The primary objective of the metal recovery stage in a hydrometallurgical process is to prepare the metal ions for subsequent leaching.
Answer: False
This statement is incorrect. The metal recovery stage is the final step in a hydrometallurgical process, aimed at producing the desired metal or metal compound in a marketable form, not for preparing ions for further leaching.
Electrowinning is a process used to recover metals by depositing them as solid precipitates from a solution onto a cathode via electrical current.
Answer: True
This is correct. Electrowinning involves using an electric current to reduce dissolved metal ions in a solution (electrolyte) to their solid metallic form, which is then deposited onto a cathode.
Electrorefining is a process primarily employed for the extraction of metals directly from low-grade ores.
Answer: False
This statement is incorrect. Electrorefining is a purification process used for metals that have already been extracted and concentrated, typically involving the dissolution of an impure anode and the deposition of a purer metal onto a cathode. Electrowinning is used for extraction from leach solutions.
Precipitation occurs when the concentration of a species in solution falls below its solubility limit.
Answer: False
This is incorrect. Precipitation occurs when the concentration of a species in solution *exceeds* its solubility limit, causing it to form an insoluble solid phase.
Precipitation is employed to remove contaminants by converting them into soluble compounds within the solution.
Answer: False
This statement is incorrect. Precipitation removes contaminants by converting them into *insoluble* compounds that can then be separated from the solution, not soluble ones.
Which of the following is NOT a primary method for metal recovery in hydrometallurgy?
Answer: Roasting
Roasting is a pre-treatment process, typically associated with pyrometallurgy or preparing ores for leaching, not a primary method for recovering metals from solution in hydrometallurgy. Electrolysis, gaseous reduction, and precipitation are key recovery techniques.
How does electrowinning recover metals like copper?
Answer: By depositing solid copper metal onto a cathode using an electric current.
Electrowinning recovers copper by passing an electric current through a solution containing copper ions, causing the metallic copper to deposit onto the cathode.
What is the distinction between electrowinning and electrorefining?
Answer: Electrowinning recovers metals from leach solutions, while electrorefining purifies metals using an impure anode.
Electrowinning extracts metals from solutions onto a cathode, whereas electrorefining purifies metals by using an impure metal as the anode and depositing a purer form onto the cathode.
Precipitation is utilized in hydrometallurgy to:
Answer: Form a solid compound from a solution when its concentration exceeds solubility.
Precipitation is the process by which a solid forms and separates from a solution when the concentration of a solute exceeds its solubility limit.
Which process involves using electricity to deposit metals from a solution, such as recovering copper?
Answer: Electrowinning
Electrowinning is the electrochemical process used to recover metals from solution by depositing them onto a cathode using an applied electric current.
The Beverley uranium deposit is cited as a primary example where heap leaching is the predominant extraction method.
Answer: False
This statement is incorrect. The Beverley uranium deposit is specifically noted as an example where in-situ leaching is the primary extraction technique, not heap leaching.
Hydrometallurgy was historically employed for copper extraction in Germany during the 17th century.
Answer: True
This is correct. Historical records indicate that hydrometallurgical techniques were indeed utilized for copper extraction in regions such as Germany and Spain during the 17th century.
In the 17th century, hydrometallurgy was applied in Spain for the extraction of gold.
Answer: False
This is incorrect. While hydrometallurgy was used in Spain during the 17th century, its primary application at that time was for the extraction of copper, not gold.
Which group of metals is specifically mentioned as being extracted using hydrometallurgy?
Answer: Rare earth elements
Hydrometallurgy is a critical technique for the extraction and separation of rare earth elements, a group of 17 chemically similar metallic elements.
The Beverley uranium deposit is noted as a practical application of which hydrometallurgical technique?
Answer: In-situ leaching
The Beverley uranium deposit serves as a prominent example demonstrating the successful implementation of in-situ leaching for mineral extraction.
Historically, hydrometallurgy was employed for copper extraction in which regions during the 17th century?
Answer: Germany and Spain
During the 17th century, hydrometallurgical techniques were applied for copper extraction in European countries, notably Germany and Spain.
What chemical compound, represented by [Au(CN)₂]⁻, is formed during the heap-leaching of low-grade gold ore?
Answer: Dicyanoaurate(I)
The heap-leaching of gold using cyanide results in the formation of the soluble dicyanoaurate(I) complex, [Au(CN)₂]⁻.