You must have had soda before, and you probably used a can as well. But if were to ask you what's inside that raised ring on the edge of the can, you probably wouldn't have a clue. Let's rule out one option first—the ring is not hollow. I bet you can't figure it out no matter how hard you try. In reality, that ring contains liquid. But what kind of liquid is it? Let me explain. The contents of that ring are closely related to the manufacturing process of the can itself. In fact, the can is made of aluminum sheets. These sheets are about 0.3 millimeters thick and are formed by being pressed against a tool called a drawing die. Continuing from there, a cylindrical object (unch) is forcefully from the top down into the aluminum sheet, forming a short cylindrical object resembling an ashtray. This process is called drawing. However, with just one drawing step, the circular disc is still wide and thick, and it has not yet reached the final shape of a beverage can. Therefore, further drawing is required. Each subsequent stamping process thins out the cylinder formed by the aluminum sheet, reducing its radius and increasing its height. After several stamping processes, the initially round sheet takes on the of a beverage can. Now, only two steps remain to complete the manufacturing process of a beverage can. The first step is to create the concave bottom of the can, and the second step is to seal it with a lid. To create the concave bottom, a tool with a rounded dome shape is used. The process is similar to stamping, where the can is pressed onto the semi-spherical tool to form the concave shape. But why does the can a concave bottom.Because the concave bottom, like an arch bridge, can withstand greater pressure. All of these steps together take only about one-seventh of a second. After trimming the top of the can neatly, it can be sprayed with outer packaging. The inside of the aluminum can also needs to be coated, otherwise acidic beverages will react with the aluminum, and you would end up consuming a lot of aluminum, which can lead to neurological disorders. (That's why they say not to eat youtiao made with alum, same principle.) Next, a thinner neck is pulled out for the can to prevent the thin aluminum from wrinkling. Now, it's time for the most crucial part - sealing the beverage can. Firstly, the edge of the neck is folded to form a flange. Then comes the fascinating process of double seaming. Back in 1810, tin cans were invented, and initially, the can lid and bottom were directly welded to the cylindrical can, resulting in food contamination from the welding materials like lead. Nowadays, beverage cans commonly employ double seaming to eliminate such issues. Double seaming is a relatively recent invention. In 1894, Ams machine company started producing double seaming machines for canning. What does double seaming mean? The flange and the lid form a shape resembling a spring roll. Although double seaming may seem ordinary, it requires high precision. A difference of just 1 millimeter can lead to a failed sealing process. However, double seaming alone cannot completely seal the can from the inside and outside. Do you see the gaps within this double seaming layer? These gaps are filled with a liquid sealing compound to prevent gas from escaping through the gaps in the seam and to safeguard the can from external contaminants.

According to the latest data from the International Aluminum Institute (IAI), 2022 marked an important milestone in the aluminum industry's journey towards emission reduction. Despite a global increase in aluminum production, it was the first year that witnessed a decrease in the total greenhouse gas (GHG) emissions from the global aluminum industry, with emissions intensity per unit of primary aluminum decreasing more than the output growth. Miles Prosser, Secretary-General of the International Aluminum Institute, stated, "Our challenge lies in ensuring that we not only increase production but also reduce greenhouse gas emissions. Given the crucial role of aluminum in the overall decarbonization of the economy, global aluminum demand is expected to significantly increase in the coming decades, often resulting in higher emissions. However, the aluminum industry is actively reducing the average carbon intensity of aluminum production per metric ton." The latest data for the year 2022, which has just been compiled, reveals that global aluminum production increased by 3.9%, rising from 104.1 million metric tons to 108.2 million metric tons. However, the overall GHG emissions from the aluminum industry experienced a decrease, dropping from 1.13 billion metric tons of carbon dioxide equivalent to 1.111 billion metric tons of carbon dioxide equivalent. Furthermore, the emissions intensity of primary aluminum production (the average emissions per metric ton of primary aluminum) has consistently declined since 2019. By 2022, the emissions intensity decreased by 4.4%, going from 15.8 metric tons of carbon dioxide equivalent per metric ton of primary aluminum to 15.1 metric tons of carbon dioxide equivalent. Miles Prosser commented, "The data for 2022 demonstrates the progress made by the aluminum industry in reducing production emissions intensity. Although there is still much work to be done, 2022 marks the first year where emission reductions, through reducing emissions intensity, offset the emissions associated with production growth. This is a significant achievement."