Lead: What It Is, Properties, Importance, Uses, and Advantages

Lead is the chemical element represented by the symbol Pb and possesses the atomic number 82. It is a heavy metal with various properties that have made it useful for a range of applications. Lead is also profoundly and near-universally toxic, which has led to progressively increasing and significant restrictions on its use in most industrial and domestic applications.

Lead has been used in the production of: batteries, radiation shielding, ammunition, and soldering materials. It is also still widely used as an alloying element in various materials to facilitate free-cutting properties. This article will discuss lead, its properties, importance, uses, and advantages.

What Is Lead?

Lead was one of the first metals known to man. It does not generally exist in metallic form in nature. However, it is easily extracted from various minerals by the application of heat and charcoal. outcome.

Lead has many applications due to its: flexibility, malleability, abundance, and ease of refinement and use. Lead’s widespread use is in part explained because its properties can be enhanced by alloying it with other metals such as antimony or copper. It played a crucial role during the Industrial Revolution. Pure lead is bluish-white in color with a bright luster, and crystallizes in a face-centered cubic structure, with no known allotropic modifications. On exposure to moisture, this luster is lost through the formation of an oxide coating that protects the underlying metal, slowing bulk oxidation. 

What Are the Physical Properties of Lead?

Table 1 below lists the physical properties of lead:

Does Lead Have High Tensile Strength?

No, lead is intrinsically soft and among the most ductile of materials. It has a tensile strength of 18 MPa. Lead’s response to very slight stress/load is to distort plastically, with a virtually unmeasurably small elastic phase.

Is Lead a Type of Metal?

Yes, lead is a metal with most of the characteristic properties of the classification. It lacks only the interatomic bond strength and crystalline integrity that most metals possess, allowing easy distortion along multiple slip planes. This crystalline structure is common to ductile metals such as: gold, silver, and copper.

Is Lead an Alloy?

No. Atomic or pure lead (of various isotopes) is elemental, unique, and differentiated from all other elements by its atomic structure and the weight of the nucleus. Commercially, materials that are described as lead often carry deliberate and accidental contaminants that affect the properties of the resulting material, potentially in significant ways. Lead alloys that are often simply termed lead can have a wide range of additions that modify properties in particular and desirable ways.

To learn more, check out our guide on Alloy Types.

What Are the Chemical Properties of Lead?

The chemical properties of lead are listed in Table 2 below:

What Is the Importance of Lead?

The importance of lead has been recognized throughout history due to its unique properties and various applications. It was, in many ways, the accidental introduction to metallurgy that made ancient humans recognize the transmutative nature of rocks. Lead is used extensively as a major ingredient of lead-acid batteries and used to produce paints and corrosion-resistant pipes.

While lead has been widely used in the past, its significance has decreased greatly in recent years. This is due to growing awareness of its toxic effects on human health and the environment. Its use is now more controlled and limited to applications in which it can be safely managed and handled.

What Are the Different Uses and Applications of Lead?

Lead has historically been used in various applications due to its unique properties. These are ongoing applications for lead that are critically important:

1. Widely used in automotive, telecommunication, and backup power systems as lead-acid batteries. This is due to their ability to store and deliver DC electrical energy reliably.
2. Essential in radiation shielding in medical imaging equipment, nuclear facilities, and other applications in which protection from harmful radiation is necessary.
3. Commonly used in electronics for joining components to circuit boards. However, due to health and environmental concerns, lead-free solders are now more widely used.
4. Used in bullets and shot pellets for firearms and ammunition.
5. Used in making marine ballast and sinkers because of the high density and chemical stability of the material.
6. Widely used as a weight for equipment balancing, particularly vehicle wheels.

How Is Lead Used in the Manufacturing Process?

Lead remains a key component in several raw materials and processes. Its most important manufacturing applications are in:

1. Lead-acid batteries, where lead is converted to lead sulfate by the sulphuric acid component, during discharge. Recharge is a reverse reaction in which the plates are reduced to pure metal by the applied current.
2. Lead is used to make free-machining brass, although this excludes the material from many applications.
3. Lead is also added to steel at around 0.25% to improve its machinability.
4. Radiation shielding made from lead is widely added to terrestrial equipment that is either very sensitive or a deliberate (radiation) source. It is not used in aerospace applications, because the weight cost is excessive.

Is Lead Used in Die Casting?

Yes, lead and lead-based alloys have been historically used in die-casting processes, although applications for this are much reduced because of toxicity-related restrictions. In lead die casting, molten lead is injected into a die to faithfully reproduce the cavity shape. This process was commonly used in the manufacture of products such as: pipes, toys, and many small electrical and plumbing components.

What Are the Sources of Lead?

Lead is widely present in the Earth’s crust in various natural rocks and minerals. The most widespread lead-containing minerals include: galena (lead sulfide), cerussite (lead carbonate), and anglesite (lead sulfate). The production of new lead results from mining and smelting these minerals, where they are found in concentrated deposits. Half of the lead used in industrial applications comes from recycling existing products and components. 

How Is Lead Mined?

Lead is principally extracted from its ores, which are found around the globe. There are various methods of extracting lead ore, depending on the type of deposit and its location. The most common method is open-cast mining, though some underground mining is still undertaken. The extracted ore is transported to a processing plant. It is crushed and ground into smaller particles to increase the surface area for reactive chemical processing. In this step, the crushed ore is concentrated to increase the valued proportion. 

Various techniques, such as froth flotation or gravity separation are used to separate the lead-bearing minerals from the gangue (unwanted materials). Once the lead ore is concentrated, it is smelted to extract the metal. Smelting involves heating the concentrated ore along with other materials (fluxes and reducing agents) in a furnace. The crude metal obtained from smelting may still contain impurities. The lead is refined by various arcane and modern processes to remove these impurities and obtain high-purity lead metal. The refined lead is cast into ingots for transportation and industrial use.

What Are the Different Types of Lead?

Commercially, lead exists in a variety of forms that are essentially alloys, although many are simply referred to as “lead”. Listed below are the common types of lead:

1. Lead Arsenatic

Lead arsenate is the term commonly used to describe lead compounds that contain arsenic (symbol As) as a part of their chemical composition. The physical and chemical properties of specific lead arsenate compounds vary depending on their composition. Lead arsenate compounds are generally solids at room temperature and may exhibit different colors and crystal structures. Lead arsenate (PbHAsO4) compounds have historically been used in various applications, including insecticides and pesticides. In the past, such agricultural products were used to control pests on crops. However, due to the serious effects both on the users and the consumers of foods produced through their use, such compounds have been largely phased out or banned in many countries. Regulatory measures and awareness have led to the restriction or elimination of many of these compounds from commercial and industrial use.

2. Lead Calcium

Lead calcium is an alloy used in lead-acid batteries in which the electrodes are made of lead alloyed with calcium. This battery alloy delivers some advantages over traditional lead-antimony battery plates. The introduction of calcium in the lead electrode plates improves several aspects of the battery's performance, inducing: reduced water consumption, longer functional life, and lower outgassing during recharge.

Lead-calcium batteries are a like-for-like alternative to lead-antimony batteries. They are common in automotive vehicles, uninterruptible power supply (UPS) systems, and other stationary power applications. They offer lower maintenance requirements, reduced water consumption, and greater tolerance for deep cycling with less plate degradation.

Lead-acid battery technology, including lead-calcium batteries, remains widely used despite the availability of newer, higher-power-density, and more robust technologies like lithium-ion and lithium-iron-phosphate. Lead-acid batteries are still favored for certain applications due to their price, reliability, and ability to survive the high current drain required for starting engines and powering certain equipment.

3. Leaded Copper

Lead-copper is a family of alloys that use two ranges of proportions of the two metals to create materials with unique properties. Low lead content of 2–4% is typical in copper which requires free machining characteristics. Where the desired material is for plain bearings, it is common to use around 10% tin in copper to improve its strength. Up to 25% lead is also used as a separate particulate phase in the alloy, to improve the bearing properties. Lead is close to insoluble in copper, so it does not form part of the matrix but exists as distinct inclusions.

The physical and chemical properties of lead-copper alloys depend on the proportion of lead and copper in the alloy. Generally, lead-copper alloys are relatively soft and have low tensile strength compared to pure copper. The addition of lead reduces their mechanical properties but enhances certain other characteristics, such as machinability and lubricity.

Lead-copper alloys are engineered to combine the desirable properties of both constituents. The addition of lead makes the material easier to cut, shape, and form. It also increases lubricity, reducing friction and wear in plain bearing applications. Some common uses and applications include: electrical contacts and connectors, bushings, sleeve bearings, and thrust washers.

4. Pure Lead

Pure lead refers to a metal that is not combined with any other elements or metals. It is a single, homogeneous substance of high purity. High-purity lead is a soft, dense, bluish-gray metal with a relatively low melting point. It is extremely malleable and ductile. It also has a low recrystallization temperature. 

Pure lead is relatively unreactive in ambient conditions. It can slowly react with moist air and certain alkali and acidic chemicals, forming lead compounds over time. It is a moderate conductor of electricity and has very low tensile strength. In its pure form, it is used for: radiation shielding in X-ray rooms, nuclear facilities, radiation-sensitive equipment, and other types of personnel protection against harmful radiation. 

While pure lead has various useful applications, it is also a supremely toxic substance. Prolonged exposure to lead, especially in its compound forms, can be harmful to human health and the environment. Therefore, safety measures and regulations are in place to minimize lead exposure and promote the use of safer alternatives in certain applications.

5. Lead-Based Babbitt Metal

Lead-based Babbitt metal, more commonly referred to as Babbitt metals or alloys, often contain lead as their primary component. Babbitt metal is used as a bearing material due to its low friction and excellent bearing properties. It contains tin, antimony, and copper, which lend structure to the otherwise somewhat formless lead. The specific composition varies by application, but lead is commonly the dominant element.

Babbitt metal is soft and malleable with a low melting point. It is easy to cast into restricted sections and precise shapes. Babbitt metal has a white (oxidized) or silver-gray (newly minted) appearance. It can be easily distinguished from other metals by an unusual combination of softness (on the Mohs scratch resilience scale) and stiffness.

Babbitt metal is primarily used for manufacturing plain bearings. They are widely used in machinery and engines, associated with pressurized oil galleries. Babbitt bearings also support rotating shafts in electric motors and generators and industrial equipment, such as: pumps, compressors, and even gas turbines.

6. Chemical Lead

Chemical lead is a moderately pure metal that has been purified to contain a low copper level of between 0.04 and 0.08% and a residual silver content of 0.002 to 0.02%. This grade is indicative of the grades mined in South Eastern Missouri. It has significantly improved corrosion resistance and slightly greater mechanical strength than many other grades of lead.

Chemical lead is only distinguishable from other grades of lead by spectrographic analysis. Its improved corrosion resistance, however, will become evident over long use in more harsh conditions. In application terms, it is interchangeable with other high-purity grades, although some applications—for example, chemical equipment—can benefit from improved corrosion resistance and strength. 

7. Antimonial Lead

The alloying of antimony with lead results in improvements to various properties. It is suitable for applications in which moderate mechanical loading is expected and self-supporting structures are called for. Antimonial lead has a bluish-gray appearance when newly cast/cut, similar to pure lead. The addition of antimony increases the alloy's hardness and strength compared to pure lead. The chemical properties of antimonial lead are influenced by the presence of both constituents, with antimony triggering the alloy's unique characteristics.

Antimonial lead alloys are used in various applications as a substitute for high-purity lead, due to the beneficial effect of antimony on the properties. The antimony also improves resistance to wear, making it suitable for components in which durability is more essential.

8. Linotype Alloy

Linotype lead is a specialist alloy that was common in the linotype printing process. The Linotype machine revolutionized the printing industry by enabling faster and more efficient typesetting. Linotype lead is primarily lead, with the addition of small amounts of other metals, such as antimony and tin. Linotype lead is a dense and malleable metal with a relatively low melting point, deriving from its primary constituent. It can be readily melted for casting into whole-line text slugs for the Linotype machine. The additions of tin and antimony make the material slightly tougher and stronger, better able to withstand the handling and installation process in the printer, and better able to endure the wear of longer print runs without degradation.

What Are the Advantages of Lead?

Lead metal has a surprising range of commercial and industrial advantages. These are listed below:

1. It is the most dense (non-radioactive) common metal, which makes it invaluable for applications requiring high weight with small volumes.
2. Is highly ductile and malleable.
3. Has a relatively low melting point compared to most metals.
4. Can absorb and dampen sound vibrations.
5. Has good resistance to corrosion, especially in non-acidic environments. 
6. Excellent material for radiation shielding in medical and nuclear applications due to its massive nucleus and resultant high density.
7. Relatively abundant and easy to refine, making it cost-effective compared to many other metals.

What Are the Disadvantages of Lead?

Lead metal has several commercial and industrial disadvantages which are listed below:

1. It is a highly toxic metal that can have severe health effects on virtually all living organisms. Prolonged exposure to lead, especially through ingestion or inhalation of lead particles or fumes, can lead to lead poisoning.
2. Lead can leach into soil and water from lead-based products. It contaminates the surrounding environment and poses generalized and enduring risks to wildlife and ecosystems.
3. Recycling of lead can be complex and is regulated to enforce careful handling and management, to avoid work-related exposure and the release of toxic materials.

Why Is Lead Considered Harmful?

Lead is harmful due to its generalized toxic properties and adverse effects on human/animal health and the environment. It is a highly toxic metal, and even at trace levels of exposure, it is generally harmful to humans and animals. It has a wide range of harmful effects and accretes in fatty tissues, among which are nerves and the brain.

Net high exposure to lead will result in lead poisoning, with severe and often irreversible health effects. This is particularly dangerous for children and pregnant women, as it can impair cognitive development, cause learning disabilities, and damage brain function. Additionally, lead pollution can contaminate soil, water, and air and result in long-lasting and insidious effects that are generational threats. Lead does not break down easily in the environment and can remain in soil and water for long periods, persisting in damage to living organisms for decades.

Can You Recover From Lead Poisoning?

Yes. It is possible to largely or fully recover from lead poisoning if the exposure is identified, removed early, and appropriate medical intervention is provided. The extent of recovery depends on the severity of lead poisoning and how quickly it is addressed. Childhood developmental effects are, however, not reversible even if the lead is entirely removed.

Chelation is an effective therapy that uses a form of chemotherapy, based on materials that chemically bind to lead in the bloodstream. This turns the lead into salts that are blood transported and excreted through urine. This is typically reserved for patients with high lead levels, or when lead poisoning symptoms are severe because the associated risks of the treatment are potentially high. Elevated intake of calcium, iron, and zinc complexes in the diet (or as supplements) can help reduce lead absorption in the body.

Summary

This article presented lead, explained it, and discussed its properties and uses. To learn more about lead, contact a Xometry representative.

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