1. A direct reduction plant for producing direct reduced iron (DRI) comprising
- a reactor (1) having a central reduction area (2) and configured so that iron oxide, in form of pellets or lumps, is introduced at the top of the reactor, while direct reduced iron is extracted at the bottom of the reactor;
- at least one inlet duct (3), defining an axis X, for introducing a mixture of reducing gas into the reactor (1), said at least one inlet duct (3) being connected to the reactor (1) at said central reduction area (2);
- a plurality of first oxygen injection ducts (4), arranged on the at least one inlet duct (3), adapted to inject oxygen into said at least one inlet duct (3);
- two or more second injection ducts (5) arranged on the at least one inlet duct (3) downstream or upstream of said plurality of first injection ducts (4), and adapted to inject pulverized lignite into said at least one inlet duct (3), wherein said two or more second injection ducts (5) are provided in an even number and arranged diametrically opposite one another, or wherein said two or more second injection ducts (5) are arranged offset to one another;
- first feeding means for feeding pulverized lignite to said two or more second injection ducts (5).

2. A plant according to claim 1, wherein the first injection ducts (4) are arranged on the inlet duct (3) radially with respect to the axis X, preferably at an equal angular distance from one another with respect to the axis X.
3. A plant according to claim 1 or 2, wherein, in the case in which the two or more second injection ducts (5) are arranged offset to one another, said two or more second injection ducts (5) are offset so as to be arranged along a circumference but not diametrically opposite one another, or offset so as not to be arranged along a circumference but offset along a longitudinal extension of the at least one inlet duct (3).
4. A plant according to anyone of the preceding claims, wherein the minimum distance along the axis X between the first injection ducts (4) and the at least one second injection duct (5) is from 400 to 600 mm, preferably from 450 to 550 mm.
5. A plant according to any one of the preceding claims, wherein said first feeding means comprise at least one drying device (13) for drying the lignite and/or at

least one grinding device (14) for grinding the lignite and obtaining pulverized lignite, and/or at least one pressurization device (15) for pressurizing said pulverized lignite towards said at least one second injection duct (5).
6. A plant according to any one of the preceding claims, wherein the inlet duct (3) is the end part of a treatment and feeding line (11), arranged upstream of the reactor (1), adapted to treat process gas, obtaining a mixture of reducing gas, and to feed said mixture of reducing gas into the reactor (1) by means of said inlet duct (3); and wherein said treatment and feeding line (11) is connected upstream to at least one external source (26) of natural gas or reforming gas and preferably comprises a possible humidifier (27) and a heating unit (12), or comprises a reformer.
7. A plant according to claim 6, wherein there is provided a recovery and treatment line (10) for the exhaust gas exiting the reactor (1), communicating upstream with the reactor (1) and downstream with said treatment and feeding line (11).
8. A direct iron ore reduction process for producing direct reduced iron (DRI), implementable by means of a plant according to any one of the preceding claims, the process comprising the following steps:

a) feeding a process gas into the inlet duct (3);
b) injecting oxygen into said inlet duct (3) by means of said first injection ducts (4), and injecting pulverized lignite into said inlet duct (3) by means of said two or more second injection ducts (5), downstream or upstream of said first injection ducts (4), so as to produce a mixture of reducing gas;
c) introducing the mixture of reducing gas into the reactor (1).
9. A process according to claim 8, wherein, before step b) the lignite is dried and
ground until a granulometry of less than 200 µm is obtained, preferably less than
or equal to 150 µm, even more preferably equal to approximately 40-150 µm.
10. A process according to claim 8 or 9, wherein the pulverized lignite composition comprises: volatile substances > 40%; fixed carbon < 50%; ash < 7%; preferably 40% < volatile substances < 52%; 42% < fixed carbon < 50%; 2% < ash < 7%.
11. A process according to any one of claims from 8 to 10, wherein the two or more second injection ducts (5) inject pulverized lignite and natural gas, with a natural gas flow rate equal to 3.5-8.5 Nm3/tDRI at a temperature of 25-350°C, and a

pulverized lignite flow rate equal to 0.04-0.06 t/tDRI, wherein tDRI is one ton of DRI obtained by direct iron ore reduction by means of the reactor (1).
12. A process according to claim 11, wherein the first injection ducts (4) inject oxygen and possibly natural gas at a temperature of 280-300°C, with an oxygen flow rate equal to 20-70 Nm3/tDRI and a possible natural gas flow rate equal to 40-60 Nm3/tDRI.
13. A process according to any one of claims from 8 to 12, wherein the temperature of the mixture of reducing gas is equal to 1000-1150°C and the flow rate of said mixture of reducing gas is equal to 1570-2500 Nm3/tDRI, wherein tDRI is one ton of DRI obtained by direct iron ore reduction by means of the reactor (1).
14. A process according to any one of claims from 10 to 13, wherein the temperature of the process gas introduced into the inlet duct (3) is equal to 900-950°C and the flow rate of said process gas is equal to 1420-2500 Nm3/tDRI, wherein tDRI is one ton of DRI obtained by direct iron ore reduction by means of the reactor (1).
15. A process according to claim 14, wherein said process gas is a natural gas or reforming gas from an external source (26) or a mixture of gases obtained by mixing the natural gas or reforming gas from said external source (26) with an exhaust gas exiting the reactor (1) and treated in a recovery and treatment line (10).