The mining industry plays a vital role in supporting the global economy. It digs up, processes, and sells a variety of metals, minerals, and energy products that are essential to the growth of many varied sectors. Iron ore, for example, is a key component in steel, while the automotive and aerospace sectors use lots of aluminum, and copper is crucial for electricity production.

Because of that, the mining sector is also an important one for investors. In 2018, the world's 40 largest publicly traded mining companies hauled in $683 billion in revenue and generated $165 billion in EBITDA. That gave them the funds to pay their shareholders a record $43 billion in dividends that year. Those cash payments, as well as the sector's upside to the growing economy and key trends like renewable energy, are why investors should consider digging into the mining industry and take a closer look at some of the mining companies that thrive in this sector.

Digging into the 10 biggest mining stocks

To assist in that pursuit, here are the 10 biggest publicly traded mining companies in the world as ranked by their market capitalization, or the sum of the company's total available shares multiplied by its stock price:

Data source: PwC, YCharts, and company websites. Market cap data is current as of mid-September 2019.

Here's a closer look at the portfolios and growth prospects of these top 10 mining stocks.

1. BHP Group

BHP Group is the largest mining company in the world by market capitalization. The company operates three segments:

• Minerals Australia: This unit consists of the company's mines in that country. They produce copper, iron ore, coal, and nickel.
• Minerals Americas: BHP's mining business in Canada, Chile, Peru, the U.S., Colombia, and Brazil. The company's assets and projects in these countries focus on copper, zinc, iron ore, coal, and potash.
• Petroleum: This business segment contains BHP's oil and gas operations in the U.S., Australia, and Trinidad and Tobago.

BHP's biggest moneymaker in 2018 was iron ore, which accounted for 39% of the group's underlying EBITDA. Copper followed at 28%, with coal at 19%, and oil and gas contributing 14% of the company's profitability.

The crown jewel of BHP's mining empire is Western Australia Iron Ore (WAIO). It's an integrated system of five mines and four processing hubs connected by more than 600 miles of railway infrastructure and port facilities. WAIO produced 275 megatons (Mt) of iron ore in 2018. That output made BHP Group one of the three biggest global producers.

Iron ore will remain a key part of BHP's portfolio in the future. That's because the company and its partners started the South Flank expansion of WAIO in 2018. The company expects to complete the $3.6 billion project by 2021. It will help replace the production of the 80 Mt per year Yandi mine that will reach the end of its useful life in the early to mid-2020s.

The company also has large projects underway in the copper and petroleum sectors. The $2.5 billion Spence Growth Option, for example, will add 185 kilotons of copper production when it comes on line in 2021. Meanwhile, the roughly $2.2 billion Mad Dog Phase 2 project will be able to produce 140,000 barrels of oil per day when it starts up in 2022. Finally, the company is developing the Jansen Potash mine in Canada. Projects like these will enable BHP Group to remain a top-tier global resources company in the coming decade.

2. Rio Tinto

Rio Tinto is a large, diversified mining company. It operates the following business segments:

• Aluminum: Rio Tinto is a global leader in aluminum, with assets in Australia, Brazil, Canada, Guinea, Iceland, New Zealand, and Oman. It operates a portfolio of large-scale, high-quality bauxite mines and alumina refineries as well as the world's most modern cost-competitive aluminum smelters.
• Iron ore: The company operates the world's largest and lowest-cost integrated iron ore business in Australia.
• Copper and diamonds: Rio Tinto owns interests in copper mines in Mongolia, the U.S., and Chile. It's also one of the world's leading diamond producers, with mines in Canada and Australia.
• Energy and minerals: Rio Tinto operates uranium mines in Australia and Namibia. The company is also a world leader in borates, one of the world's largest producers of seaborne salt, and a leader in producing high-grade titanium dioxide.

Iron ore is by far Rio Tinto's biggest moneymaker. In 2018, that metal supplied 62% of the company's underlying EBITDA. Aluminum was second at 17% of the total, followed by copper and diamonds at 15%, and energy and minerals at 12%.

Rio Tinto plans to invest more than $6 billion annually through 2021 to sustain and grow its mining output. The company has projects underway to develop an underground copper mine in Mongolia, expand an existing copper mine in the U.S., replace depleting iron ore mines in Australia, and extend the life of a mineral deposit in South Africa. The company also has projects in development to potentially build a large copper mine in the U.S. and exploit a lithium deposit in Serbia. These investments and development projects have Rio Tinto well positioned for the future growth demand, especially given the significant need for copper and lithium by the renewable energy sector.

3. Vale

Vale is a large diversified mining company based in Brazil. It's the world's largest producer of iron ore and nickel. Vale also produces significant amounts of copper, coal, and manganese.

Vale operates 22 iron ore mines in the Carajas region of Brazil. Rocks in this region contain 67% iron ore, which is the highest concentration in the world. In addition to its mines, Vale operates plants that produce iron ore pellets and has an extensive railway and port infrastructure to get its production to global markets. In 2018, Vale's iron ore business supplied 74% of its revenue, followed by nickel at 13% and copper at 6%.

Iron ore will remain crucial to Vale in the coming years. It spent $14.3 billion to develop the S11D iron ore complex. Production from that mine is on track to increase from 55 Mt per year in 2018 up to 90 Mt per year by 2020. It's investing another $770 million to boost S11D's production capacity up to 100 Mt by 2022 and to expand its Northern System's logistics capability so that it can handle 240 Mt per year. Those are just some of the projects the company has underway to improve its iron ore, copper, coal, and nickel operations in the coming years. Those projects ensure that Vale will remain a top-tier mining company over the next decade.

4. Glencore

Glencore is among the world's largest and most diversified natural resource companies. It operates 150 mining and metallurgical sites as well as oil and gas production assets and agricultural facilities. In addition to producing commodities, the company markets them from third-party miners.

In 2018, Glencore's industrial mining business made most of is money on coal at 33% of the group's underlying EBITDA. Copper was a close second at 30%, followed by zinc at 15%, and nickel at 5%. The company's third-party marketing business, meanwhile, supplied another 15% of its earnings in 2018.

Glencore expects to invest an average of $3.6 billion per year through 2021 to sustain its existing operations and another $1.2 billion annually on expansion projects. Those growth-related investments have the company on track to increase its coal output by 10% over that time frame, while copper production should rise 3%, and zinc should surge 28%. The company also anticipates even faster production growth from smaller product groups like cobalt (74% growth by 2021) and oil (183% higher by 2021). As a result, Glencore will become even more diversified in the future even as its earnings increase (assuming commodity prices cooperate).

5. China Shenhua Energy

China Shenhua Energy is the largest coal mining company in the world. The Chinese company operates coal mines in the country as well as an integrated rail network and a seaport that it uses to transport coal. China Shenhua also operates power plants that generate electricity from coal that it sells to utilities.

Its coal mining business supplied 61% of its total revenue in 2018. Power generation was its next biggest revenue contributor at 33% of the total while its railway, port, shipping, and coal chemical operations chipped in the rest.

China was the world's largest coal consumer in 2018 at nearly half of the global total. While it will likely remain the leader in burning coal in the coming years, the country is working hard to reduce its usage. Consequently, forecasters at the International Energy Agency anticipate that China's demand for coal will drop 3% by 2023. That will likely put pressure on China Shenhua Energy's coal business in the coming years, which could cause it to slide down the leaderboard.

6. MMC Norilsk Nickel (Nornickel)

Mining and Metallurgical Company (MMC) Norilsk Nickel is a Russian mining company. It's the global leader in producing high-grade refined nickel as well as palladium. It's also the fourth-largest producer of both platinum and rhodium and the 11th biggest copper miner. Nornickel also produces some gold, silver, iridium, selenium, ruthenium, and tellurium.

The company supplied 39% of the world's palladium in 2018, enabling that metal to contribute 34% of Nornickel's revenue. It also produced 23% of the world's high-grade nickel, which in turn supplied 28% of its revenue. Copper, meanwhile, was its next biggest revenue contributor at 27% of the total even though Nornickel only produced 2% of global copper supplies.

Nornickel has several projects underway and in development to grow its production in the coming years. Because of that, the company believes it can increase its nickel and copper production by 15% by 2025, while its palladium and platinum output are on track to expand by 25%. Given those growth prospects, Nornickel could climb up the global leaderboard in the coming years.

7. Newmont Goldcorp

Newmont Goldcorp is the top gold mining company in the world by production volume. The company formed in 2019 after the merger of leading gold mining companies Newmont Mining and Goldcorp. The combined company operates a portfolio of 14 gold mines in North and South America, Africa, and Australia as well as stakes in two gold mining joint ventures (JVs). In addition to gold, these mines also produce some zinc, lead, silver, and copper.

Gold, however, is by far Newmont Goldcorp's biggest revenue generator at more than 90% of the combined company's total in 2018. It should remain that way in the coming years given that the company is targeting to produce between 6 million and 7 million ounces of gold per year through 2025. It's aiming to achieve that goal by investing in projects to sustain its existing mines and build new ones. Those investments should help offset production declines as its legacy mines deplete.

One of the projects it's considering is spending $650 million to $750 million on the second expansion of its Tanami mine in Australia. That project would add 100,000 ounces of annual production in the 2023 to 2027 time frame while extending the mine's life until 2040. Projects like that should enable Newmont Goldcorp to remain one of the world's largest mining companies in the years ahead.

8. AngloAmerican

AngloAmerican is a diversified mining company. It produces copper, coal, diamonds, iron ore, platinum group metals, nickel, and manganese. The U.K.-based company operates mines in Africa, North and South America, and Australia.

AngloAmerican made most of its money on coal in 2018, at 35% of its total EBITDA. Copper was second at 20%, followed by iron ore at 16% and its investment in De Beers -- the world's leading diamond company -- providing another 14% of its earnings that year.

The company has several projects underway to expand its mining production. In AngloAmerican's view, it can increase its copper equivalent production by 20%-25% from 2018's level by 2023. That's a much faster growth rate than its large diversified peers, which forecast production growth rates in the 5% to 15% range over that time frame. Because of its faster growth rate, AngloAmerican appears poised to climb up the leaderboard in the coming years.

9. Barrick Gold

Barrick Gold, which expects to produce between 5.1 million and 5.6 million ounces in 2019, is among the world's top gold miners by volume. It operates mines in North and South America, Africa, the Middle East, and Australia. In addition to gold, Barrick also produces copper. Gold, though, accounted for 91% of its revenue in 2018, with copper a distant second at 7%.

Barrick Gold's focus is on operating Tier 1 mines. It defines that as a mine with more than 10 years of remaining life, at least 500,000 ounce of annual gold production, and total cash costs per ounce in the bottom half of gold mines operated by its publicly traded peers. Thus, these mines should deliver lots of steady, low-cost production, which will enable Barrick to make more money over the long term.

Given this focus on owning Tier 1 mines, Barrick Gold isn't aiming to increase its production. Because of that, the company's output could decline in the coming years as it sells noncore mines. However, it does have some enticing growth projects in development, including a 50% stake in Donlin Gold, which is one of the world's largest undeveloped gold deposits. As it develops these and other Tier 1 mining projects, Barrick should remain among the world's largest mining companies.

10. Grupo Mexico

Grupo Mexico is a diversified mining and industrial holding company in Mexico. It's one of the world's largest copper producers by volume. That's due to its majority stake in top-10 copper producer Southern Copper (NYSE:SCCO), which operates mines in Mexico and Peru. Grupo Mexico also holds stakes in mining companies in the U.S. and Spain. These entities produce copper, silver, molybdenum, zinc, sulfuric acid, gold, and selenium. Copper, however, accounts for 80% of the mining group's sales.

In addition to mining, Grupo Mexico operates the largest rail transport company in Mexico. It also owns stakes in several industrial businesses focused on engineering, construction, power generation, and oil drilling services.

The crown jewel of Grupo Mexico's mining portfolio is its 88.9% interest in Southern Copper. That company produced 884 kilotons of copper in 2018, which made it the fifth-largest in that sector. It's also one of the lowest-cost copper producers in the world.

Southern Copper has the second-largest known copper reserves in the world. Based on that, the company believes that it can significantly increase its copper output in the coming years by investing in expanding its existing mines and building new ones. In its estimation, its copper production could reach 1,800 kilotons by 2026. That will benefit Grupo Mexico's mining business, potentially enabling it to climb up the leaderboard in the coming years.

The world's largest mining companies have varying focuses

The world's largest mining companies fall into two categories. Some operate a diversified portfolio of mines while others focus on one specific commodity. That gives investors two distinct opportunity sets with very different risk/reward profiles.

Diversified miners, for example, give investors broad exposure to the entire sector, which helps reduce risk. However, that dilutes an investor's exposure to specific metals that they might want to focus on, such as copper (for renewable energy) and gold (for safety during economic downturns). More focused miners, on the other hand, have higher risk profiles but also more direct upside potential. So, investors interested in mining stocks have to decide whether they want the lower risk profile of a diversified miner or the higher reward potential of a focused miner.

Another important factor to consider is the mining company's growth prospects. Those focused on coal, for example, will be under pressure as that fossil fuel becomes less essential in powering the global economy in the future. Therefore, investors need to zero in on companies that are mining the right materials so that they can benefit from the sector's growth potential.