Chemical power sources can be divided into three types: primary batteries, secondary batteries (also known as batteries) and fuel cells. As the name implies, a primary battery is a battery that is discarded after one use. For example, zinc-manganese dry batteries, zinc-silver button batteries, etc.
- 1. What is zinc manganese dry battery
- 2. Reaction principle of zinc-manganese dry battery
- 3. Recovery and disposal of zinc-manganese dry batteries
1. What is zinc manganese dry battery
Zinc-manganese dry batteries are primary batteries in chemical power sources. The batteries that are discarded after one use are divided into acidic and alkaline zinc-manganese dry batteries.
There are two types of zinc-manganese dry batteries: acid zinc-manganese dry batteries and alkaline zinc-manganese dry batteries.
1. Acid zinc manganese dry battery
The acid zinc-manganese dry battery uses a zinc cylinder as the negative electrode and is treated with amalgamation to make the surface properties more uniform, so as to reduce the corrosion of zinc and improve the storage performance of the battery. The positive electrode material is made of manganese dioxide powder, ammonium chloride and A mixed paste composed of carbon black. A carbon rod is inserted between the positive electrode material as a conductor for drawing current. There is a layer of reinforced separator paper between the positive electrode and the negative electrode, which is impregnated with ammonium chloride and zinc chloride In the electrolyte solution, the upper part of the metallic zinc is sealed.
2. Alkaline zinc manganese dry battery
Alkaline zinc manganese battery is abbreviated as alkaline manganese battery. It was successfully developed in 1882, developed in 1912, and came into production in 1949. It was found that when KOH electrolyte solution was used instead of NH4Cl as the electrolyte, both the electrolyte and the structure There are big changes in the above, and the specific energy and discharge current of the battery can be significantly improved.
2. Reaction principle of zinc-manganese dry battery
The main working principle of the zinc-manganese dry battery is that the oxidation-reduction reaction is realized in a closed loop! (It is very similar to the original battery, which is to convert chemical energy into electrical energy)
For example: the electrode reaction formula of alkaline zinc manganese dry battery is: Zn+2MnO2+2NH4Cl= ZnCl2++Mn2O3+2NH3+H2O
The cylinder made of metal zinc skin is the negative electrode. The discharge of the battery is the electrolysis reaction of ammonia chloride and zinc. The charge released is conducted by graphite to the positive electrode carbon rod. The electrolysis reaction of zinc will release hydrogen gas, which will increase the gas. The internal resistance of the battery, and the manganese dioxide mixed with graphite is used to absorb hydrogen. However, if the battery works continuously or is used for too long, the manganese dioxide will be too late or nearly saturated and unable to absorb it again. At this time, the battery will lose its function due to too much internal resistance and too little output current. But at this time, if the battery is heated or left for a period of time, the accumulated hydrogen gas inside it will be released by heat or slowly.
3. Recovery and disposal of zinc-manganese dry batteries
The recycling of zinc-manganese dry batteries mainly solves two problems. The first is the recycling of metallic mercury and other useful substances, and the second is the treatment of waste gas, waste liquid and waste residue. The “roasting-electrolysis” recovery treatment process mainly includes roasting, liquid production, electrolysis, waste gas, waste residue treatment and other processes.
1. First, the waste zinc-manganese battery is mechanically cut, and carbon rods, copper caps, and plastics are sorted out, so that the powder and zinc cylinders inside the battery are fully exposed.
2. Recycle the carbon rods, copper caps, and plastics.
3. The unrecovered components are sent to a closed roasting furnace and roasted for 3 hours at a temperature of 600 ℃, isolated from air (thermogravimetric analysis shows that the reaction is complete at 600 ℃).
4. It is reduced to manganese monoxide during roasting, which is convenient for leaching with sulfuric acid (manganese dioxide must be dissolved with concentrated sulfuric acid and carbon powder at a temperature of 383 K). The tail gas produced by roasting contains mercury, wax, ammonia gas, and ammonia. After being exported from the roasting furnace, it passes through the condensation tank to condense and recover most of the mercury vapor. The tail gas enters the spray tank and is sprayed with water (pH = 6) to absorb Ammonia, grab money and wax.