Since 2019, 100% FDI under the automatic route has been allowed in the sale of coal and coal mining activities including associated processing infrastructure subject to the provisions of Coal Mines (Special Provisions) Act, 2015 and the Mines and Minerals (Development and Regulation) Act, 1957 as amended from time to time and other relevant Acts on the subject. 
Previously, FDI was allowed without restrictions only in (1) coal & lignite mining for captive consumption by power projects, iron & steel and cement units and other eligible activities permitted under and subject to the provisions of Coal Mines (Nationalization) Act, 1973, and (2) coal processing plants like washeries subject to the condition that the company shall not do coal mining and shall not sell washed coal or sized coal from its coal processing plants in the open market and shall supply the washed or sized coal to those parties who are supplying raw coal to coal processing plants for washing or sizing.
"CHAPTER 3: GENERAL CONDITIONS ON FDI [...]
3.4   ENTRY ROUTES FOR INVESTMENT 3.4.1 Investments can be made by non-residents in the equity shares/fully, compulsorily and mandatorily convertible debentures/fully, compulsorily and mandatorily convertible preference shares of an Indian company, through the Automatic Route or the Government Route. Under the Automatic Route, the non-resident investor or the Indian company does not require any approval from Government of India for the investment. Under the Government Route, prior approval of the Government of India is required. Proposals for foreign investment under Government Route, are considered by respective Administrative Ministry/Department. 
[...]
3.5   CAPS ON INVESTMENTS
3.5.1 Investments can be made by person resident outside India in the capital of a resident entity only to the extent of the percentage of the total capital as specified in the FDI policy. The caps in various sector(s) are detailed in Chapter 5 of this Circular. 
3.6   ENTRY CONDITIONS ON INVESTMENT
3.6.1 Investments by non-residents can be permitted in the capital of a resident entity in certain sectors/activity with entry conditions. Such conditions may include norms for minimum capitalization, lock-in period, etc. The entry conditions in various sectors/activities are detailed in Chapter 5 of this Circular.
[...]
5.2 PERMITTED SECTORS
a) In the following sectors/activities, FDI up to the limit indicated against each sector/activity is allowed, subject to applicable laws/regulations; security and other conditionalities. In sectors/activities not listed below, FDI is permitted up to100% on the automatic route, subject to applicable laws/regulations; security and other conditionalities. [...]
c) Foreign investment in sectors under Government approval route resulting in transfer of ownership and/or control of Indian entities from resident Indian citizens to nonresident entities will be subject to Government approval. Foreign investment in sectors under automatic route but with conditionalities, resulting in transfer of ownership and/or control of Indian entities from resident Indian citizens to non-resident entities, will be subject to compliance of such conditionalities. 
[...]
5.2.3 MINING 
Sector/Activity | % of Equity/ FDI Cap | Entry Route 
5.2.3.1  Mining and Exploration of metal and non-metal ores including diamond, gold, silver and precious ores but excluding titanium bearing minerals and its ores; subject to the Mines and Minerals (Development & Regulation) Act, 1957. | % of Equity/FDI Cap: 100% | Entry Route: Automatic
5.2.3.2  Coal & Lignite
(1) Coal & Lignite mining for captive consumption by power projects, iron & steel and cement units and other eligible activities permitted under and subject to the provisions of Coal Mines (Special Provisions) Act, 2015 and the Mines and Minerals (Development and Regulation) Act, 1957.
(2) Setting up coal processing plants like washeries subject to the condition that the company shall not do coal mining and shall not sell washed coal or sized coal from its coal processing plants in the open market and shall supply the washed or sized coal to those parties who are supplying raw coal to coal processing plants for washing or sizing.
(3) For sale of coal, coal mining activities including associated processing infrastructure subject to the provisions of Coal Mines (Special Provisions) Act, 2015 and the Mines and Minerals (Development and Regulation) Act, 1957 as amended from time to time and other relevant Acts on the subject. | % of Equity/FDI Cap: 100% | Entry Route: Automatic
[...]
5.2.3.3.2 OTHER CONDITIONS 
(ii)  FDI will not be allowed in mining of "prescribed substances" listed in the Notification No. S.O. 61(E), dated 18.1.2006, issued by the Department of Atomic Energy.
(iii) "Associated Processing Infrastructure" as contained at Para 5.2.3.2 above includes coal washery, crushing, coal handling, and separation (magnetic and non-magnetic) [...]" (Government of India/Ministry of Commerce and Industry (2020), Consolidated FDI Policy (Effective from October 15, 2020))
------------------------------
"S.O. 1592(E).—In pursuance of clauses (f) and (g) of sub-section (1) of Section 2 and Section 3 of the Atomic Energy Act, 1962 (No. 33 of 1962) and in supersession of the notifications of the Government of India in the Department of Atomic Energy vide number S.O. 61(E) dated 20th January 2006, the Central Government hereby notifies the substances, equipment and technology specified in the Schedule appended hereto as 'Prescribed Substances, Prescribed Equipment and Technology'. 
SCHEDULE 
Category 0 Nuclear materials, nuclear-related other materials, equipment and technology
0A  PRESCRIBED SUBSTANCES 
Note: Any radioactive material in Category 0A shall additionally attract the provisions of Radiation Protection Rules, 2004 made under the Atomic Energy Act, 1962 and the provisions of Section-16 of the Atomic Energy Act, 1962. 
0A1 Source Material
0A101 Uranium containing the mixture of isotopes occurring in nature.
0A102 Uranium depleted in the isotope 235.
0A103 Thorium. 
[...]
0A2 Special Fissionable Material
0A201 Plutonium-239.
0A202 Uranium-233. 
[...]
0A3 Other Materials
'Other Materials' means non-nuclear materials for reactors, nuclear related dual-use materials indicated below and such materials as determined by the Central Government from time to time. [e.g. Deuterium, Zirconium, Beryllium, Lithium, Niobbium and Tantalum, Tritium, Radium, Boron, Helium]
[...]
0B Prescribed Equipment
0B001 Nuclear Reactors; associated equipment, components, and systems especially designed, prepared, or adapted or used or intended to be used in such reactors including but not limited to:- [...]
0B002 Plants for processing, production, concentration, conversion or recovery of Prescribed Substances (such as uranium, plutonium, thorium, deuterium, heavy water, tritium, lithium); associated equipment, components and systems especially designed, prepared or adapted or used or intended to be used in such plants including but not limited to:
[...]
0C Technology and software 
Technology and software for the development, production or use of prescribed substances or prescribed equipment specified in 0A or 0B. [...]" (DEPARTMENT OF ATOMIC ENERGY  NOTIFICATION F. No. 32/02/2016-ER, "Update of the List of Prescribed Substances, Prescribed Equipment and Technology Under Atomic Energy Act 1962, 28 April, 2016)
------------------------------
Previously up to 2019
------------------------------
"5.2.3 MINING 
Sector/Activity | % of Equity/ FDI Cap | Entry Route
5.2.3.1  Mining and Exploration of metal and non-metal ores including diamond, gold, silver and precious ores but excluding titanium bearing minerals  and its ores; subject to the Mines and Minerals (Development & Regulation) Act, 1957. | % of Equity/FDI Cap: 100% | Entry Route: Automatic
5.2.3.2  Coal & Lignite
(1) Coal & Lignite mining for captive consumption by power projects, iron & steel and cement units and other eligible activities permitted under and subject to the provisions of Coal Mines (Nationalization) Act, 1973. 
(2) Setting up coal processing plants like washeries subject to the condition that the company shall not do coal mining and shall not sell washed coal or sized coal from its coal processing plants in the open market and shall supply the washed or sized coal to those parties who are supplying raw coal to coal processing plants for washing or sizing. | % of Equity/FDI Cap: 100% | Entry Route: Automatic
[...]
5.2.3.3.2 OTHER CONDITIONS 
(ii)  FDI will not be allowed in mining of "prescribed substances" listed in the Notification No. S.O. 61(E), dated 18.1.2006, issued by the Department of Atomic Energy.
(iii) "Associated Processing Infrastructure" as contained at Para 5.2.3.2 above includes coal washery, crushing, coal handling, and separation (magnetic and non-magnetic) [...]" (Government of India/Ministry of Commerce and Industry (2017), Consolidated FDI Policy (Effective from August 28, 2017))
Government of India/Ministry of Commerce and Industry (2020), Consolidated FDI Policy (Effective from October 15, 2020)
Government of India/Ministry of Commerce & Industry (2019), Press Note Press Note No. 4 (2019 Series)
DEPARTMENT OF ATOMIC ENERGY  NOTIFICATION F. No. 32/02/2016-ER, "Update of the List of Prescribed Substances, Prescribed Equipment and Technology Under Atomic Energy Act 1962, 28 April, 2016
Government of India/Ministry of Commerce and Industry (2017), Consolidated FDI Policy (Effective from August 28, 2017)
[<a href="https://dpiit.gov.in/sites/default/files/FDI-PolicyCircular-2020-29October2020_0.pdf">Policy</a>],[<a href="https://dpiit.gov.in/sites/default/files/pn4_2019.pdf">PN</a>],[<a href="https://dae.gov.in/writereaddata/pres_subs_0516.pdf">Notification</a>],[<a href="https://dpiit.gov.in/sites/default/files/CFPC_2017_FINAL_RELEASED_28.8.17_0.pdf">Policy</a>]